[IR] Switch everything to use memory attribute

This switches everything to use the memory attribute proposed in
https://discourse.llvm.org/t/rfc-unify-memory-effect-attributes/65579.
The old argmemonly, inaccessiblememonly and inaccessiblemem_or_argmemonly
attributes are dropped. The readnone, readonly and writeonly attributes
are restricted to parameters only.

The old attributes are auto-upgraded both in bitcode and IR.
The bitcode upgrade is a policy requirement that has to be retained
indefinitely. The IR upgrade is mainly there so it's not necessary
to update all tests using memory attributes in this patch, which
is already large enough. We could drop that part after migrating
tests, or retain it longer term, to make it easier to import IR
from older LLVM versions.

High-level Function/CallBase APIs like doesNotAccessMemory() or
setDoesNotAccessMemory() are mapped transparently to the memory
attribute. Code that directly manipulates attributes (e.g. via
AttributeList) on the other hand needs to switch to working with
the memory attribute instead.

Differential Revision: https://reviews.llvm.org/D135780

1 files changed, 77 insertions, 13 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 338674c..66b4edb 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1718,8 +1718,8 @@ static uint64_t getRawAttributeMask(Attribute::AttrKind Val) {
   case Attribute::Convergent:      return 1ULL << 46;
   case Attribute::SafeStack:       return 1ULL << 47;
   case Attribute::NoRecurse:       return 1ULL << 48;
-  case Attribute::InaccessibleMemOnly:         return 1ULL << 49;
-  case Attribute::InaccessibleMemOrArgMemOnly: return 1ULL << 50;
+  // 1ULL << 49 is InaccessibleMemOnly, which is upgraded separately.
+  // 1ULL << 50 is InaccessibleMemOrArgMemOnly, which is upgraded separately.
   case Attribute::SwiftSelf:       return 1ULL << 51;
   case Attribute::SwiftError:      return 1ULL << 52;
   case Attribute::WriteOnly:       return 1ULL << 53;
@@ -1767,7 +1767,8 @@ static void addRawAttributeValue(AttrBuilder &B, uint64_t Val) {
 /// been decoded from the given integer. This function must stay in sync with
 /// 'encodeLLVMAttributesForBitcode'.
 static void decodeLLVMAttributesForBitcode(AttrBuilder &B,
-                                           uint64_t EncodedAttrs) {
+                                           uint64_t EncodedAttrs,
+                                           uint64_t AttrIdx) {
   // The alignment is stored as a 16-bit raw value from bits 31--16.  We shift
   // the bits above 31 down by 11 bits.
   unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
@@ -1776,8 +1777,43 @@ static void decodeLLVMAttributesForBitcode(AttrBuilder &B,
 
   if (Alignment)
     B.addAlignmentAttr(Alignment);
-  addRawAttributeValue(B, ((EncodedAttrs & (0xfffffULL << 32)) >> 11) |
-                          (EncodedAttrs & 0xffff));
+
+  uint64_t Attrs = ((EncodedAttrs & (0xfffffULL << 32)) >> 11) |
+                   (EncodedAttrs & 0xffff);
+
+  if (AttrIdx == AttributeList::FunctionIndex) {
+    // Upgrade old memory attributes.
+    MemoryEffects ME = MemoryEffects::unknown();
+    if (Attrs & (1ULL << 9)) {
+      // ReadNone
+      Attrs &= ~(1ULL << 9);
+      ME &= MemoryEffects::none();
+    }
+    if (Attrs & (1ULL << 10)) {
+      // ReadOnly
+      Attrs &= ~(1ULL << 10);
+      ME &= MemoryEffects::readOnly();
+    }
+    if (Attrs & (1ULL << 49)) {
+      // InaccessibleMemOnly
+      Attrs &= ~(1ULL << 49);
+      ME &= MemoryEffects::inaccessibleMemOnly();
+    }
+    if (Attrs & (1ULL << 50)) {
+      // InaccessibleMemOrArgMemOnly
+      Attrs &= ~(1ULL << 50);
+      ME &= MemoryEffects::inaccessibleOrArgMemOnly();
+    }
+    if (Attrs & (1ULL << 53)) {
+      // WriteOnly
+      Attrs &= ~(1ULL << 53);
+      ME &= MemoryEffects::writeOnly();
+    }
+    if (ME != MemoryEffects::unknown())
+      B.addMemoryAttr(ME);
+  }
+
+  addRawAttributeValue(B, Attrs);
 }
 
 Error BitcodeReader::parseAttributeBlock() {
@@ -1824,7 +1860,7 @@ Error BitcodeReader::parseAttributeBlock() {
 
       for (unsigned i = 0, e = Record.size(); i != e; i += 2) {
         AttrBuilder B(Context);
-        decodeLLVMAttributesForBitcode(B, Record[i+1]);
+        decodeLLVMAttributesForBitcode(B, Record[i+1], Record[i]);
         Attrs.push_back(AttributeList::get(Context, Record[i], B));
       }
 
@@ -1851,8 +1887,6 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::Alignment;
   case bitc::ATTR_KIND_ALWAYS_INLINE:
     return Attribute::AlwaysInline;
-  case bitc::ATTR_KIND_ARGMEMONLY:
-    return Attribute::ArgMemOnly;
   case bitc::ATTR_KIND_BUILTIN:
     return Attribute::Builtin;
   case bitc::ATTR_KIND_BY_VAL:
@@ -1869,10 +1903,6 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::ElementType;
   case bitc::ATTR_KIND_FNRETTHUNK_EXTERN:
     return Attribute::FnRetThunkExtern;
-  case bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY:
-    return Attribute::InaccessibleMemOnly;
-  case bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY:
-    return Attribute::InaccessibleMemOrArgMemOnly;
   case bitc::ATTR_KIND_INLINE_HINT:
     return Attribute::InlineHint;
   case bitc::ATTR_KIND_IN_REG:
@@ -2039,6 +2069,31 @@ Error BitcodeReader::parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind) {
   return Error::success();
 }
 
+static bool upgradeOldMemoryAttribute(MemoryEffects &ME, uint64_t EncodedKind) {
+  switch (EncodedKind) {
+  case bitc::ATTR_KIND_READ_NONE:
+    ME &= MemoryEffects::none();
+    return true;
+  case bitc::ATTR_KIND_READ_ONLY:
+    ME &= MemoryEffects::readOnly();
+    return true;
+  case bitc::ATTR_KIND_WRITEONLY:
+    ME &= MemoryEffects::writeOnly();
+    return true;
+  case bitc::ATTR_KIND_ARGMEMONLY:
+    ME &= MemoryEffects::argMemOnly();
+    return true;
+  case bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY:
+    ME &= MemoryEffects::inaccessibleMemOnly();
+    return true;
+  case bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY:
+    ME &= MemoryEffects::inaccessibleOrArgMemOnly();
+    return true;
+  default:
+    return false;
+  }
+}
+
 Error BitcodeReader::parseAttributeGroupBlock() {
   if (Error Err = Stream.EnterSubBlock(bitc::PARAMATTR_GROUP_BLOCK_ID))
     return Err;
@@ -2082,10 +2137,16 @@ Error BitcodeReader::parseAttributeGroupBlock() {
       uint64_t Idx = Record[1]; // Index of the object this attribute refers to.
 
       AttrBuilder B(Context);
+      MemoryEffects ME = MemoryEffects::unknown();
       for (unsigned i = 2, e = Record.size(); i != e; ++i) {
         if (Record[i] == 0) {        // Enum attribute
           Attribute::AttrKind Kind;
-          if (Error Err = parseAttrKind(Record[++i], &Kind))
+          uint64_t EncodedKind = Record[++i];
+          if (Idx == AttributeList::FunctionIndex &&
+              upgradeOldMemoryAttribute(ME, EncodedKind))
+            continue;
+
+          if (Error Err = parseAttrKind(EncodedKind, &Kind))
             return Err;
 
           // Upgrade old-style byval attribute to one with a type, even if it's
@@ -2159,6 +2220,9 @@ Error BitcodeReader::parseAttributeGroupBlock() {
         }
       }
 
+      if (ME != MemoryEffects::unknown())
+        B.addMemoryAttr(ME);
+
       UpgradeAttributes(B);
       MAttributeGroups[GrpID] = AttributeList::get(Context, Idx, B);
       break;