[llvm-commits] [llvm] r166313 - in /llvm/trunk: lib/Transforms/Scalar/SimplifyLibCalls.cpp test/Transforms/SimplifyLibCalls/FFS.ll

[Benjamin Kramer]

Author: d0k
Date: Fri Oct 19 15:43:44 2012
New Revision: 166313

URL: http://llvm.org/viewvc/llvm-project?rev=166313&view=rev
Log:
SimplifyLibcalls: The return value of ffsll is always i32, even when the input is zero.

Fixes PR13028.

Modified:
    llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
    llvm/trunk/test/Transforms/SimplifyLibCalls/FFS.ll

Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp?rev=166313&r1=166312&r2=166313&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp Fri Oct 19 15:43:44 2012
@@ -772,8 +772,8 @@
 
     // Constant fold.
     if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
-      if (CI->getValue() == 0)  // ffs(0) -> 0.
-        return Constant::getNullValue(CI->getType());
+      if (CI->isZero()) // ffs(0) -> 0.
+        return B.getInt32(0);
       // ffs(c) -> cttz(c)+1
       return B.getInt32(CI->getValue().countTrailingZeros() + 1);
     }

Modified: llvm/trunk/test/Transforms/SimplifyLibCalls/FFS.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyLibCalls/FFS.ll?rev=166313&r1=166312&r2=166313&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyLibCalls/FFS.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyLibCalls/FFS.ll Fri Oct 19 15:43:44 2012
@@ -1,6 +1,7 @@
-; Test that the ToAsciiOptimizer works correctly
-; RUN: opt < %s -simplify-libcalls -S | \
-; RUN:   not grep "call.*@ffs"
+; Test that FFSOpt works correctly
+; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
+
+; CHECK-NOT: call{{.*}}@ffs
 
 @non_const = external global i32		; <i32*> [#uses=1]
 
@@ -34,3 +35,11 @@
         %2 = call i32 @ffsll(i64 %0)            ; <i32> [#uses=1]
         ret i32 %2
 }
+
+; PR13028
+define i32 @b() nounwind {
+  %ffs = call i32 @ffsll(i64 0)
+  ret i32 %ffs
+; CHECK: @b
+; CHECK-NEXT: ret i32 0
+}