[attrs] Extract the pure inference of function attributes into

a standalone pass.

There is no call graph or even interesting analysis for this part of
function attributes -- it is literally inferring attributes based on the
target library identification. As such, we can do it using a much
simpler module pass that just walks the declarations. This can also
happen much earlier in the pass pipeline which has benefits for any
number of other passes.

In the process, I've cleaned up one particular aspect of the logic which
was necessary in order to separate the two passes cleanly. It now counts
inferred attributes independently rather than just counting all the
inferred attributes as one, and the counts are more clearly explained.

The two test cases we had for this code path are both ... woefully
inadequate and copies of each other. I've kept the superset test and
updated it. We need more testing here, but I had to pick somewhere to
stop fixing everything broken I saw here.

Differential Revision: http://reviews.llvm.org/D15676

llvm-svn: 256466

1 files changed, 1 insertions, 852 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index b268eff..6dcfb3f 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -50,7 +50,6 @@ STATISTIC(NumReadNoneArg, "Number of arguments marked readnone");
 STATISTIC(NumReadOnlyArg, "Number of arguments marked readonly");
 STATISTIC(NumNoAlias, "Number of function returns marked noalias");
 STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
-STATISTIC(NumAnnotated, "Number of attributes added to library functions");
 STATISTIC(NumNoRecurse, "Number of functions marked as norecurse");
 
 namespace {
@@ -942,48 +941,6 @@ static bool addNonNullAttrs(const SCCNodeSet &SCCNodes,
   return MadeChange;
 }
 
-static void setDoesNotAccessMemory(Function &F) {
-  if (!F.doesNotAccessMemory()) {
-    F.setDoesNotAccessMemory();
-    ++NumAnnotated;
-  }
-}
-
-static void setOnlyReadsMemory(Function &F) {
-  if (!F.onlyReadsMemory()) {
-    F.setOnlyReadsMemory();
-    ++NumAnnotated;
-  }
-}
-
-static void setDoesNotThrow(Function &F) {
-  if (!F.doesNotThrow()) {
-    F.setDoesNotThrow();
-    ++NumAnnotated;
-  }
-}
-
-static void setDoesNotCapture(Function &F, unsigned n) {
-  if (!F.doesNotCapture(n)) {
-    F.setDoesNotCapture(n);
-    ++NumAnnotated;
-  }
-}
-
-static void setOnlyReadsMemory(Function &F, unsigned n) {
-  if (!F.onlyReadsMemory(n)) {
-    F.setOnlyReadsMemory(n);
-    ++NumAnnotated;
-  }
-}
-
-static void setDoesNotAlias(Function &F, unsigned n) {
-  if (!F.doesNotAlias(n)) {
-    F.setDoesNotAlias(n);
-    ++NumAnnotated;
-  }
-}
-
 static bool setDoesNotRecurse(Function &F) {
   if (F.doesNotRecurse())
     return false;
@@ -992,809 +949,6 @@ static bool setDoesNotRecurse(Function &F) {
   return true;
 }
 
-/// Analyze the name and prototype of the given function and set any applicable
-/// attributes.
-///
-/// Returns true if any attributes were set and false otherwise.
-static bool inferPrototypeAttributes(Function &F, const TargetLibraryInfo &TLI) {
-  if (F.hasFnAttribute(Attribute::OptimizeNone))
-    return false;
-
-  FunctionType *FTy = F.getFunctionType();
-  LibFunc::Func TheLibFunc;
-  if (!(TLI.getLibFunc(F.getName(), TheLibFunc) && TLI.has(TheLibFunc)))
-    return false;
-
-  switch (TheLibFunc) {
-  case LibFunc::strlen:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setOnlyReadsMemory(F);
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::strchr:
-  case LibFunc::strrchr:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isIntegerTy())
-      return false;
-    setOnlyReadsMemory(F);
-    setDoesNotThrow(F);
-    break;
-  case LibFunc::strtol:
-  case LibFunc::strtod:
-  case LibFunc::strtof:
-  case LibFunc::strtoul:
-  case LibFunc::strtoll:
-  case LibFunc::strtold:
-  case LibFunc::strtoull:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::strcpy:
-  case LibFunc::stpcpy:
-  case LibFunc::strcat:
-  case LibFunc::strncat:
-  case LibFunc::strncpy:
-  case LibFunc::stpncpy:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::strxfrm:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::strcmp: // 0,1
-  case LibFunc::strspn:  // 0,1
-  case LibFunc::strncmp: // 0,1
-  case LibFunc::strcspn: // 0,1
-  case LibFunc::strcoll: // 0,1
-  case LibFunc::strcasecmp:  // 0,1
-  case LibFunc::strncasecmp: //
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setOnlyReadsMemory(F);
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::strstr:
-  case LibFunc::strpbrk:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setOnlyReadsMemory(F);
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::strtok:
-  case LibFunc::strtok_r:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::scanf:
-    if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::setbuf:
-  case LibFunc::setvbuf:
-    if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::strdup:
-  case LibFunc::strndup:
-    if (FTy->getNumParams() < 1 || !FTy->getReturnType()->isPointerTy() ||
-        !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::stat:
-  case LibFunc::statvfs:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::sscanf:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::sprintf:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::snprintf:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(2)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 3);
-    setOnlyReadsMemory(F, 3);
-    break;
-  case LibFunc::setitimer:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy() ||
-        !FTy->getParamType(2)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    setDoesNotCapture(F, 3);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::system:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    // May throw; "system" is a valid pthread cancellation point.
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::malloc:
-    if (FTy->getNumParams() != 1 || !FTy->getReturnType()->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    break;
-  case LibFunc::memcmp:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setOnlyReadsMemory(F);
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::memchr:
-  case LibFunc::memrchr:
-    if (FTy->getNumParams() != 3)
-      return false;
-    setOnlyReadsMemory(F);
-    setDoesNotThrow(F);
-    break;
-  case LibFunc::modf:
-  case LibFunc::modff:
-  case LibFunc::modfl:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::memcpy:
-  case LibFunc::memccpy:
-  case LibFunc::memmove:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::memalign:
-    if (!FTy->getReturnType()->isPointerTy())
-      return false;
-    setDoesNotAlias(F, 0);
-    break;
-  case LibFunc::mkdir:
-    if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::mktime:
-    if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::realloc:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getReturnType()->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::read:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    // May throw; "read" is a valid pthread cancellation point.
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::rewind:
-    if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::rmdir:
-  case LibFunc::remove:
-  case LibFunc::realpath:
-    if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::rename:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::readlink:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::write:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    // May throw; "write" is a valid pthread cancellation point.
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::bcopy:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::bcmp:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setOnlyReadsMemory(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::bzero:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::calloc:
-    if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    break;
-  case LibFunc::chmod:
-  case LibFunc::chown:
-    if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::ctermid:
-  case LibFunc::clearerr:
-  case LibFunc::closedir:
-    if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::atoi:
-  case LibFunc::atol:
-  case LibFunc::atof:
-  case LibFunc::atoll:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setOnlyReadsMemory(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::access:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::fopen:
-    if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
-        !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::fdopen:
-    if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::feof:
-  case LibFunc::free:
-  case LibFunc::fseek:
-  case LibFunc::ftell:
-  case LibFunc::fgetc:
-  case LibFunc::fseeko:
-  case LibFunc::ftello:
-  case LibFunc::fileno:
-  case LibFunc::fflush:
-  case LibFunc::fclose:
-  case LibFunc::fsetpos:
-  case LibFunc::flockfile:
-  case LibFunc::funlockfile:
-  case LibFunc::ftrylockfile:
-    if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::ferror:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F);
-    break;
-  case LibFunc::fputc:
-  case LibFunc::fstat:
-  case LibFunc::frexp:
-  case LibFunc::frexpf:
-  case LibFunc::frexpl:
-  case LibFunc::fstatvfs:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::fgets:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(2)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 3);
-    break;
-  case LibFunc::fread:
-    if (FTy->getNumParams() != 4 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(3)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 4);
-    break;
-  case LibFunc::fwrite:
-    if (FTy->getNumParams() != 4 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(3)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 4);
-    break;
-  case LibFunc::fputs:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::fscanf:
-  case LibFunc::fprintf:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::fgetpos:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::getc:
-  case LibFunc::getlogin_r:
-  case LibFunc::getc_unlocked:
-    if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::getenv:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setOnlyReadsMemory(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::gets:
-  case LibFunc::getchar:
-    setDoesNotThrow(F);
-    break;
-  case LibFunc::getitimer:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::getpwnam:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::ungetc:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::uname:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::unlink:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::unsetenv:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::utime:
-  case LibFunc::utimes:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::putc:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::puts:
-  case LibFunc::printf:
-  case LibFunc::perror:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::pread:
-    if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    // May throw; "pread" is a valid pthread cancellation point.
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::pwrite:
-    if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    // May throw; "pwrite" is a valid pthread cancellation point.
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::putchar:
-    setDoesNotThrow(F);
-    break;
-  case LibFunc::popen:
-    if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
-        !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::pclose:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::vscanf:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::vsscanf:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy() ||
-        !FTy->getParamType(2)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::vfscanf:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy() ||
-        !FTy->getParamType(2)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::valloc:
-    if (!FTy->getReturnType()->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    break;
-  case LibFunc::vprintf:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::vfprintf:
-  case LibFunc::vsprintf:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::vsnprintf:
-    if (FTy->getNumParams() != 4 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(2)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 3);
-    setOnlyReadsMemory(F, 3);
-    break;
-  case LibFunc::open:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    // May throw; "open" is a valid pthread cancellation point.
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::opendir:
-    if (FTy->getNumParams() != 1 || !FTy->getReturnType()->isPointerTy() ||
-        !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::tmpfile:
-    if (!FTy->getReturnType()->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    break;
-  case LibFunc::times:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::htonl:
-  case LibFunc::htons:
-  case LibFunc::ntohl:
-  case LibFunc::ntohs:
-    setDoesNotThrow(F);
-    setDoesNotAccessMemory(F);
-    break;
-  case LibFunc::lstat:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::lchown:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::qsort:
-    if (FTy->getNumParams() != 4 || !FTy->getParamType(3)->isPointerTy())
-      return false;
-    // May throw; places call through function pointer.
-    setDoesNotCapture(F, 4);
-    break;
-  case LibFunc::dunder_strdup:
-  case LibFunc::dunder_strndup:
-    if (FTy->getNumParams() < 1 || !FTy->getReturnType()->isPointerTy() ||
-        !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::dunder_strtok_r:
-    if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::under_IO_getc:
-    if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::under_IO_putc:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::dunder_isoc99_scanf:
-    if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::stat64:
-  case LibFunc::lstat64:
-  case LibFunc::statvfs64:
-    if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::dunder_isoc99_sscanf:
-    if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::fopen64:
-    if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
-        !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    setOnlyReadsMemory(F, 1);
-    setOnlyReadsMemory(F, 2);
-    break;
-  case LibFunc::fseeko64:
-  case LibFunc::ftello64:
-    if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    break;
-  case LibFunc::tmpfile64:
-    if (!FTy->getReturnType()->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotAlias(F, 0);
-    break;
-  case LibFunc::fstat64:
-  case LibFunc::fstatvfs64:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
-      return false;
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 2);
-    break;
-  case LibFunc::open64:
-    if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy())
-      return false;
-    // May throw; "open" is a valid pthread cancellation point.
-    setDoesNotCapture(F, 1);
-    setOnlyReadsMemory(F, 1);
-    break;
-  case LibFunc::gettimeofday:
-    if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
-        !FTy->getParamType(1)->isPointerTy())
-      return false;
-    // Currently some platforms have the restrict keyword on the arguments to
-    // gettimeofday. To be conservative, do not add noalias to gettimeofday's
-    // arguments.
-    setDoesNotThrow(F);
-    setDoesNotCapture(F, 1);
-    setDoesNotCapture(F, 2);
-    break;
-  default:
-    // Didn't mark any attributes.
-    return false;
-  }
-
-  return true;
-}
-
 static bool addNoRecurseAttrs(const CallGraphSCC &SCC,
                               SmallVectorImpl<WeakVH> &Revisit) {
   // Try and identify functions that do not recurse.
@@ -1874,18 +1028,13 @@ bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
       continue;
     }
 
-    // When initially processing functions, also infer their prototype
-    // attributes if they are declarations.
-    if (F->isDeclaration())
-      Changed |= inferPrototypeAttributes(*F, *TLI);
-
     SCCNodes.insert(F);
   }
 
   Changed |= addReadAttrs(SCCNodes, AARGetter);
   Changed |= addArgumentAttrs(SCCNodes);
 
-  // If we have no external nodes participating in the SCC, we can infer some
+  // If we have no external nodes participating in the SCC, we can deduce some
   // more precise attributes as well.
   if (!ExternalNode) {
     Changed |= addNoAliasAttrs(SCCNodes);