[llvm] r275039 - Pointer-comparison folding should look through returned-argument functions

[Hal Finkel via llvm-commits]

Author: hfinkel
Date: Sun Jul 10 22:37:59 2016
New Revision: 275039

URL: http://llvm.org/viewvc/llvm-project?rev=275039&view=rev
Log:
Pointer-comparison folding should look through returned-argument functions

For functions which are known to return a specific argument, pointer-comparison
folding can look through the function calls as part of its analysis.

Differential Revision: http://reviews.llvm.org/D9387

Added:
    llvm/trunk/test/Transforms/InstSimplify/returned.ll
Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=275039&r1=275038&r2=275039&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Sun Jul 10 22:37:59 2016
@@ -621,6 +621,11 @@ static Constant *stripAndComputeConstant
         break;
       V = GA->getAliasee();
     } else {
+      if (auto CS = CallSite(V))
+        if (Value *RV = CS.getReturnedArgOperand()) {
+          V = RV;
+          continue;
+        }
       break;
     }
     assert(V->getType()->getScalarType()->isPointerTy() &&

Added: llvm/trunk/test/Transforms/InstSimplify/returned.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/returned.ll?rev=275039&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/returned.ll (added)
+++ llvm/trunk/test/Transforms/InstSimplify/returned.ll Sun Jul 10 22:37:59 2016
@@ -0,0 +1,30 @@
+; RUN: opt -instsimplify -S < %s | FileCheck %s
+
+define i1 @bitcast() {
+; CHECK-LABEL: @bitcast(
+  %a = alloca i32
+  %b = alloca i64
+  %x = bitcast i32* %a to i8*
+  %z = bitcast i64* %b to i8*
+  %y = call i8* @func1(i8* %z)
+  %cmp = icmp eq i8* %x, %y
+  ret i1 %cmp
+; CHECK-NEXT: ret i1 false
+}
+
+%gept = type { i32, i32 }
+
+define i1 @gep3() {
+; CHECK-LABEL: @gep3(
+  %x = alloca %gept, align 8
+  %a = getelementptr %gept, %gept* %x, i64 0, i32 0
+  %y = call %gept* @func2(%gept* %x)
+  %b = getelementptr %gept, %gept* %y, i64 0, i32 1
+  %equal = icmp eq i32* %a, %b
+  ret i1 %equal
+; CHECK-NEXT: ret i1 false
+}
+
+declare i8* @func1(i8* returned) nounwind readnone
+declare %gept* @func2(%gept* returned) nounwind readnone
+