Added instcombine pattern to spot comparing -val or val against 0.
(val != 0) == (-val != 0) so "abs(val) != 0" becomes "val != 0"
Fixes <rdar://problem/10482509>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145563 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 274758c..cebe37b 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1795,6 +1795,20 @@
if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
+ // comparing -val or val with non-zero is the same as just comparing val
+ // ie, (val != 0) == (-val != 0)
+ if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero()))
+ {
+ Value *Cond, *SubSrc, *SelectFalse;
+ if (match(Op0, m_Select(m_Value(Cond), m_Sub(m_Zero(), m_Value(SubSrc)),
+ m_Value(SelectFalse)))) {
+ if (SubSrc == SelectFalse) {
+ return CmpInst::Create(Instruction::ICmp, I.getPredicate(),
+ SubSrc, Op1);
+ }
+ }
+ }
+
Type *Ty = Op0->getType();
// icmp's with boolean values can always be turned into bitwise operations