[llvm-commits] [llvm] r170020 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineCompares.cpp test/Transforms/InstCombine/icmp.ll

[David Majnemer]

Author: majnemer
Date: Wed Dec 12 14:48:54 2012
New Revision: 170020

URL: http://llvm.org/viewvc/llvm-project?rev=170020&view=rev
Log:
Simplify negated bit test

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
    llvm/trunk/test/Transforms/InstCombine/icmp.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=170020&r1=170019&r2=170020&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Wed Dec 12 14:48:54 2012
@@ -2034,6 +2034,15 @@
                                                CI->countTrailingZeros()));
       }
 
+      // Turn x&~y == 0 into x&y != 0 if x is a power of 2.
+      Value *X = 0, *Y = 0;
+      if (match(Op0, m_And(m_Value(X), m_Not(m_Value(Y)))) &&
+          match(Op1, m_Zero()) && isPowerOfTwo(X, TD)) {
+        return new ICmpInst(ICmpInst::ICMP_NE,
+                            Builder->CreateAnd(X, Y),
+                            Op1);
+      }
+
       break;
     }
     case ICmpInst::ICMP_NE: {
@@ -2071,6 +2080,15 @@
                                                CI->countTrailingZeros()));
       }
 
+      // Turn x&~y != 0 into x&y == 0 if x is a power of 2.
+      Value *X = 0, *Y = 0;
+      if (match(Op0, m_And(m_Value(X), m_Not(m_Value(Y)))) &&
+          match(Op1, m_Zero()) && isPowerOfTwo(X, TD)) {
+        return new ICmpInst(ICmpInst::ICMP_EQ,
+                            Builder->CreateAnd(X, Y),
+                            Op1);
+      }
+
       break;
     }
     case ICmpInst::ICMP_ULT:

Modified: llvm/trunk/test/Transforms/InstCombine/icmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp.ll?rev=170020&r1=170019&r2=170020&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/icmp.ll Wed Dec 12 14:48:54 2012
@@ -677,3 +677,29 @@
 ; CHECK-NEXT: ret i1 true
   ret i1 %cmp
 }
+
+define i1 @test67(i32 %A, i32 %B) {
+  %neg = xor i32 %A, -1
+  %shl = shl i32 1, %B
+  %and = and i32 %shl, %neg
+  %cmp = icmp ne i32 %and, 0
+; CHECK: @test67
+; CHECK-NEXT: %shl = shl i32 1, %B
+; CHECK-NEXT: %1 = and i32 %shl, %A
+; CHECK-NEXT: %cmp = icmp eq i32 %1, 0
+; CHECK-NEXT: ret i1 %cmp
+  ret i1 %cmp
+}
+
+define i1 @test68(i32 %A, i32 %B) {
+  %neg = xor i32 %A, -1
+  %shl = shl i32 1, %B
+  %and = and i32 %shl, %neg
+  %cmp = icmp eq i32 %and, 0
+; CHECK: @test68
+; CHECK-NEXT: %shl = shl i32 1, %B
+; CHECK-NEXT: %1 = and i32 %shl, %A
+; CHECK-NEXT: %cmp = icmp ne i32 %1, 0
+; CHECK-NEXT: ret i1 %cmp
+  ret i1 %cmp
+}