[IR] Remove size argument from lifetime intrinsics (#150248)

Now that #149310 has restricted lifetime intrinsics to only work on
allocas, we can also drop the explicit size argument. Instead, the size
is implied by the alloca.

This removes the ability to only mark a prefix of an alloca alive/dead.
We never used that capability, so we should remove the need to handle
that possibility everywhere (though many key places, including stack
coloring, did not actually respect this).

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 2b0f212..67c2cfa 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -150,6 +150,10 @@ static ModRefInfo GetLocation(const Instruction *Inst, MemoryLocation &Loc,
     switch (II->getIntrinsicID()) {
     case Intrinsic::lifetime_start:
     case Intrinsic::lifetime_end:
+      Loc = MemoryLocation::getForArgument(II, 0, TLI);
+      // These intrinsics don't really modify the memory, but returning Mod
+      // will allow them to be handled conservatively.
+      return ModRefInfo::Mod;
     case Intrinsic::invariant_start:
       Loc = MemoryLocation::getForArgument(II, 1, TLI);
       // These intrinsics don't really modify the memory, but returning Mod
@@ -441,11 +445,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
       Intrinsic::ID ID = II->getIntrinsicID();
       switch (ID) {
       case Intrinsic::lifetime_start: {
-        // FIXME: This only considers queries directly on the invariant-tagged
-        // pointer, not on query pointers that are indexed off of them.  It'd
-        // be nice to handle that at some point (the right approach is to use
-        // GetPointerBaseWithConstantOffset).
-        MemoryLocation ArgLoc = MemoryLocation::getAfter(II->getArgOperand(1));
+        MemoryLocation ArgLoc = MemoryLocation::getAfter(II->getArgOperand(0));
         if (BatchAA.isMustAlias(ArgLoc, MemLoc))
           return MemDepResult::getDef(II);
         continue;