[llvm-commits] [llvm] r129545 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp test/Transforms/InstCombine/or.ll

[Eli Friedman]

Author: efriedma
Date: Thu Apr 14 17:41:27 2011
New Revision: 129545

URL: http://llvm.org/viewvc/llvm-project?rev=129545&view=rev
Log:
Add an instcombine for constructs like a | -(b != c); a select is more
canonical, and generally leads to better code.  Found while looking at
an article about saturating arithmetic.


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/test/Transforms/InstCombine/or.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=129545&r1=129544&r2=129545&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Thu Apr 14 17:41:27 2011
@@ -2003,7 +2003,14 @@
       }
     }
   }
-  
+
+  // or(sext(A), B) -> A ? -1 : B where A is an i1
+  // or(A, sext(B)) -> B ? -1 : A where B is an i1
+  if (match(Op0, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1))
+    return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1);
+  if (match(Op1, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1))
+    return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0);
+
   // Note: If we've gotten to the point of visiting the outer OR, then the
   // inner one couldn't be simplified.  If it was a constant, then it won't
   // be simplified by a later pass either, so we try swapping the inner/outer

Modified: llvm/trunk/test/Transforms/InstCombine/or.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/or.ll?rev=129545&r1=129544&r2=129545&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/or.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/or.ll Thu Apr 14 17:41:27 2011
@@ -390,3 +390,22 @@
 ; CHECK-NEXT: ret i1
 }
 
+define i32 @test37(i32* %xp, i32 %y) {
+; CHECK: @test37
+; CHECK: select i1 %tobool, i32 -1, i32 %x
+  %tobool = icmp ne i32 %y, 0
+  %sext = sext i1 %tobool to i32
+  %x = load i32* %xp
+  %or = or i32 %sext, %x
+  ret i32 %or
+}
+
+define i32 @test38(i32* %xp, i32 %y) {
+; CHECK: @test38
+; CHECK: select i1 %tobool, i32 -1, i32 %x
+  %tobool = icmp ne i32 %y, 0
+  %sext = sext i1 %tobool to i32
+  %x = load i32* %xp
+  %or = or i32 %x, %sext
+  ret i32 %or
+}