[llvm-commits] [llvm] r93884 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp test/Transforms/InstCombine/idioms.ll test/Transforms/InstCombine/xor2.ll

[Chris Lattner]

Author: lattner
Date: Tue Jan 19 12:16:19 2010
New Revision: 93884

URL: http://llvm.org/viewvc/llvm-project?rev=93884&view=rev
Log:
optimize ~(~X >>s Y) --> (X >>s Y), patch by Edmund Grimley
Evans!

Added:
    llvm/trunk/test/Transforms/InstCombine/idioms.ll
Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/test/Transforms/InstCombine/xor2.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=93884&r1=93883&r2=93884&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Tue Jan 19 12:16:19 2010
@@ -1751,6 +1751,11 @@
             return BinaryOperator::CreateOr(NotX, NotY);
           return BinaryOperator::CreateAnd(NotX, NotY);
         }
+
+      } else if (Op0I->getOpcode() == Instruction::AShr) {
+        // ~(~X >>s Y) --> (X >>s Y)
+        if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0)))
+          return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1));
       }
     }
   }

Added: llvm/trunk/test/Transforms/InstCombine/idioms.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/idioms.ll?rev=93884&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/idioms.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/idioms.ll Tue Jan 19 12:16:19 2010
@@ -0,0 +1,32 @@
+; RUN: opt -instcombine %s -S | FileCheck %s
+
+; Check that code corresponding to the following C function is
+; simplified into a single ASR operation:
+;
+; int test_asr(int a, int b) {
+;   return a < 0 ? -(-a - 1 >> b) - 1 : a >> b;
+; }
+;
+define i32 @test_asr(i32 %a, i32 %b) {
+entry:
+	%c = icmp slt i32 %a, 0
+	br i1 %c, label %bb2, label %bb3
+
+bb2:
+	%t1 = sub i32 0, %a
+	%not = sub i32 %t1, 1
+	%d = ashr i32 %not, %b
+	%t2 = sub i32 0, %d
+	%not2 = sub i32 %t2, 1
+	br label %bb4
+bb3:
+	%e = ashr i32 %a, %b
+	br label %bb4
+bb4:
+        %f = phi i32 [ %not2, %bb2 ], [ %e, %bb3 ]
+	ret i32 %f
+; CHECK: @test_asr
+; CHECK: bb4:
+; CHECK: %f = ashr i32 %a, %b
+; CHECK: ret i32 %f
+}

Modified: llvm/trunk/test/Transforms/InstCombine/xor2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/xor2.ll?rev=93884&r1=93883&r2=93884&view=diff

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/xor2.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/xor2.ll Tue Jan 19 12:16:19 2010
@@ -41,3 +41,13 @@
   %ov110 = xor i32 %ov31, 153
   ret i32 %ov110
 }
+
+define i32 @test4(i32 %A, i32 %B) {
+	%1 = xor i32 %A, -1
+	%2 = ashr i32 %1, %B
+	%3 = xor i32 %2, -1
+	ret i32 %3
+; CHECK: @test4
+; CHECK: %1 = ashr i32 %A, %B
+; CHECK: ret i32 %1
+}