[llvm-commits] [llvm] r50537 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/urem-simplify-bug.ll

[Dan Gohman]

Author: djg
Date: Thu May  1 14:13:24 2008
New Revision: 50537

URL: http://llvm.org/viewvc/llvm-project?rev=50537&view=rev
Log:
Fix an overaggressive SimplifyDemandedBits optimization on urem. This
fixes the 254.gap regression on x86 and the 403.gcc regression on x86-64.

Added:
    llvm/trunk/test/Transforms/InstCombine/urem-simplify-bug.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=50537&r1=50536&r2=50537&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Thu May  1 14:13:24 2008
@@ -1762,11 +1762,12 @@
 
     APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
     APInt AllOnes = APInt::getAllOnesValue(BitWidth);
-    ComputeMaskedBits(I->getOperand(0), AllOnes,
-                      KnownZero2, KnownOne2, Depth+1);
+    if (SimplifyDemandedBits(I->getOperand(0), AllOnes,
+                             KnownZero2, KnownOne2, Depth+1))
+      return true;
+
     uint32_t Leaders = KnownZero2.countLeadingOnes();
-    APInt HighZeros = APInt::getHighBitsSet(BitWidth, Leaders);
-    if (SimplifyDemandedBits(I->getOperand(1), ~HighZeros,
+    if (SimplifyDemandedBits(I->getOperand(1), AllOnes,
                              KnownZero2, KnownOne2, Depth+1))
       return true;
 

Added: llvm/trunk/test/Transforms/InstCombine/urem-simplify-bug.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/urem-simplify-bug.ll?rev=50537&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/urem-simplify-bug.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/urem-simplify-bug.ll Thu May  1 14:13:24 2008
@@ -0,0 +1,32 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {= or i32 %x, -5	}
+
+ at .str = internal constant [5 x i8] c"foo\0A\00"		; <[5 x i8]*> [#uses=1]
+ at .str1 = internal constant [5 x i8] c"bar\0A\00"		; <[5 x i8]*> [#uses=1]
+
+define i32 @main() nounwind  {
+entry:
+	%x = call i32 @func_11( ) nounwind 		; <i32> [#uses=1]
+	%tmp3 = or i32 %x, -5		; <i32> [#uses=1]
+	%tmp5 = urem i32 251, %tmp3		; <i32> [#uses=1]
+	%tmp6 = icmp ne i32 %tmp5, 0		; <i1> [#uses=1]
+	%tmp67 = zext i1 %tmp6 to i32		; <i32> [#uses=1]
+	%tmp9 = urem i32 %tmp67, 95		; <i32> [#uses=1]
+	%tmp10 = and i32 %tmp9, 1		; <i32> [#uses=1]
+	%tmp12 = icmp eq i32 %tmp10, 0		; <i1> [#uses=1]
+	br i1 %tmp12, label %bb14, label %bb
+
+bb:		; preds = %entry
+	br label %bb15
+
+bb14:		; preds = %entry
+	br label %bb15
+
+bb15:		; preds = %bb14, %bb
+	%iftmp.0.0 = phi i8* [ getelementptr ([5 x i8]* @.str1, i32 0, i32 0), %bb14 ], [ getelementptr ([5 x i8]* @.str, i32 0, i32 0), %bb ]		; <i8*> [#uses=1]
+	%tmp17 = call i32 (i8*, ...)* @printf( i8* %iftmp.0.0 ) nounwind 		; <i32> [#uses=0]
+	ret i32 0
+}
+
+declare i32 @func_11()
+
+declare i32 @printf(i8*, ...) nounwind