[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, 14 insertions, 19 deletions

diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index ff2dada..0cade0d 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1351,30 +1351,27 @@ void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
 }
 
 /// Emit a lifetime.begin marker if some criteria are satisfied.
-/// \return a pointer to the temporary size Value if a marker was emitted, null
-/// otherwise
-llvm::Value *CodeGenFunction::EmitLifetimeStart(llvm::TypeSize Size,
-                                                llvm::Value *Addr) {
+/// \return whether the marker was emitted.
+bool CodeGenFunction::EmitLifetimeStart(llvm::Value *Addr) {
   if (!ShouldEmitLifetimeMarkers)
-    return nullptr;
+    return false;
 
   assert(Addr->getType()->getPointerAddressSpace() ==
              CGM.getDataLayout().getAllocaAddrSpace() &&
          "Pointer should be in alloca address space");
-  llvm::Value *SizeV = llvm::ConstantInt::get(
-      Int64Ty, Size.isScalable() ? -1 : Size.getFixedValue());
-  llvm::CallInst *C =
-      Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {SizeV, Addr});
+  llvm::CallInst *C = Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {Addr});
   C->setDoesNotThrow();
-  return SizeV;
+  return true;
 }
 
-void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) {
+void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Addr) {
+  if (!ShouldEmitLifetimeMarkers)
+    return;
+
   assert(Addr->getType()->getPointerAddressSpace() ==
              CGM.getDataLayout().getAllocaAddrSpace() &&
          "Pointer should be in alloca address space");
-  llvm::CallInst *C =
-      Builder.CreateCall(CGM.getLLVMLifetimeEndFn(), {Size, Addr});
+  llvm::CallInst *C = Builder.CreateCall(CGM.getLLVMLifetimeEndFn(), {Addr});
   C->setDoesNotThrow();
 }
 
@@ -1632,9 +1629,8 @@ CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
         // is rare.
         if (!Bypasses.IsBypassed(&D) &&
             !(!getLangOpts().CPlusPlus && hasLabelBeenSeenInCurrentScope())) {
-          llvm::TypeSize Size = CGM.getDataLayout().getTypeAllocSize(allocaTy);
-          emission.SizeForLifetimeMarkers =
-              EmitLifetimeStart(Size, AllocaAddr.getPointer());
+          emission.UseLifetimeMarkers =
+              EmitLifetimeStart(AllocaAddr.getPointer());
         }
       } else {
         assert(!emission.useLifetimeMarkers());
@@ -1727,9 +1723,8 @@ CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
 
   // Make sure we call @llvm.lifetime.end.
   if (emission.useLifetimeMarkers())
-    EHStack.pushCleanup<CallLifetimeEnd>(NormalEHLifetimeMarker,
-                                         emission.getOriginalAllocatedAddress(),
-                                         emission.getSizeForLifetimeMarkers());
+    EHStack.pushCleanup<CallLifetimeEnd>(
+        NormalEHLifetimeMarker, emission.getOriginalAllocatedAddress());
 
   // Analogous to lifetime markers, we use a 'cleanup' to emit fake.use
   // calls for local variables. We are exempting volatile variables and