Don't insert lifetime.end markers between a musttail call and ret

The allocas going out of scope are immediately killed by the return
instruction.

This is a resend of r208912, which was committed accidentally.

Reviewers: chandlerc

Differential Revision: http://reviews.llvm.org/D3792

llvm-svn: 208920

1 files changed, 12 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index ab60a400e53..e01d0c38ec4 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -755,8 +755,13 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
       }
 
       builder.CreateLifetimeStart(AI, AllocaSize);
-      for (ReturnInst *RI : Returns)
+      for (ReturnInst *RI : Returns) {
+        // Don't insert llvm.lifetime.end calls between a musttail call and a
+        // return.  The return kills all local allocas.
+        if (InlinedMustTailCalls && getPrecedingMustTailCall(RI))
+          continue;
         IRBuilder<>(RI).CreateLifetimeEnd(AI, AllocaSize);
+      }
     }
   }
 
@@ -774,8 +779,13 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
 
     // Insert a call to llvm.stackrestore before any return instructions in the
     // inlined function.
-    for (ReturnInst *RI : Returns)
+    for (ReturnInst *RI : Returns) {
+      // Don't insert llvm.stackrestore calls between a musttail call and a
+      // return.  The return will restore the stack pointer.
+      if (InlinedMustTailCalls && getPrecedingMustTailCall(RI))
+        continue;
       IRBuilder<>(RI).CreateCall(StackRestore, SavedPtr);
+    }
   }
 
   // If we are inlining for an invoke instruction, we must make sure to rewrite