[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, 25 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 59a47a9..fa3c467 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -3004,31 +3004,11 @@ void llvm::InlineFunctionImpl(CallBase &CB, InlineFunctionInfo &IFI,
       if (hasLifetimeMarkers(AI))
         continue;
 
-      // Try to determine the size of the allocation.
-      ConstantInt *AllocaSize = nullptr;
-      if (ConstantInt *AIArraySize =
-          dyn_cast<ConstantInt>(AI->getArraySize())) {
-        auto &DL = Caller->getDataLayout();
-        Type *AllocaType = AI->getAllocatedType();
-        TypeSize AllocaTypeSize = DL.getTypeAllocSize(AllocaType);
-        uint64_t AllocaArraySize = AIArraySize->getLimitedValue();
-
-        // Don't add markers for zero-sized allocas.
-        if (AllocaArraySize == 0)
-          continue;
-
-        // Check that array size doesn't saturate uint64_t and doesn't
-        // overflow when it's multiplied by type size.
-        if (!AllocaTypeSize.isScalable() &&
-            AllocaArraySize != std::numeric_limits<uint64_t>::max() &&
-            std::numeric_limits<uint64_t>::max() / AllocaArraySize >=
-                AllocaTypeSize.getFixedValue()) {
-          AllocaSize = ConstantInt::get(Type::getInt64Ty(AI->getContext()),
-                                        AllocaArraySize * AllocaTypeSize);
-        }
-      }
+      std::optional<TypeSize> Size = AI->getAllocationSize(AI->getDataLayout());
+      if (Size && Size->isZero())
+        continue;
 
-      builder.CreateLifetimeStart(AI, AllocaSize);
+      builder.CreateLifetimeStart(AI);
       for (ReturnInst *RI : Returns) {
         // Don't insert llvm.lifetime.end calls between a musttail or deoptimize
         // call and a return.  The return kills all local allocas.
@@ -3038,7 +3018,7 @@ void llvm::InlineFunctionImpl(CallBase &CB, InlineFunctionInfo &IFI,
         if (InlinedDeoptimizeCalls &&
             RI->getParent()->getTerminatingDeoptimizeCall())
           continue;
-        IRBuilder<>(RI).CreateLifetimeEnd(AI, AllocaSize);
+        IRBuilder<>(RI).CreateLifetimeEnd(AI);
       }
     }
   }