DAGCombine: Also shrink eq compares where the constant is exactly as large as the smaller type.
if ((x & 255) == 255)
before: movzbl %al, %eax
cmpl $255, %eax
after: cmpb $-1, %al
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182038 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index f5fc66c..95c327c 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1160,7 +1160,7 @@
}
// Make sure we're not losing bits from the constant.
- if (MinBits < C1.getBitWidth() && MinBits > C1.getActiveBits()) {
+ if (MinBits < C1.getBitWidth() && MinBits >= C1.getActiveBits()) {
EVT MinVT = EVT::getIntegerVT(*DAG.getContext(), MinBits);
if (isTypeDesirableForOp(ISD::SETCC, MinVT)) {
// Will get folded away.
diff --git a/test/CodeGen/X86/shrink-compare.ll b/test/CodeGen/X86/shrink-compare.ll
index 8d4b07f..0c16f86 100644
--- a/test/CodeGen/X86/shrink-compare.ll
+++ b/test/CodeGen/X86/shrink-compare.ll
@@ -34,3 +34,19 @@
; CHECK: test2:
; CHECK: cmpb $47, %{{dil|cl}}
}
+
+define void @test3(i32 %X) nounwind {
+entry:
+ %and = and i32 %X, 255
+ %cmp = icmp eq i32 %and, 255
+ br i1 %cmp, label %if.then, label %if.end
+
+if.then:
+ tail call void @bar() nounwind
+ br label %if.end
+
+if.end:
+ ret void
+; CHECK: test3:
+; CHECK: cmpb $-1, %{{dil|cl}}
+}