[InstSimplify] More fcmp cases when comparing against negative constants.
Summary:
For known positive non-zero value X:
fcmp uge X, -C => true
fcmp ugt X, -C => true
fcmp une X, -C => true
fcmp oeq X, -C => false
fcmp ole X, -C => false
fcmp olt X, -C => false
Patch by Paul Walker.
Reviewers: majnemer, t.p.northover, spatel, RKSimon
Reviewed By: spatel
Subscribers: fhahn, llvm-commits
Differential Revision: https://reviews.llvm.org/D40012
llvm-svn: 319538
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 6bed2f3..145aa13 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3378,6 +3378,28 @@
default:
break;
}
+ } else if (C->isNegative()) {
+ assert(!C->isNaN() && "Unexpected NaN constant!");
+ // TODO: We can catch more cases by using a range check rather than
+ // relying on CannotBeOrderedLessThanZero.
+ switch (Pred) {
+ case FCmpInst::FCMP_UGE:
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_UNE:
+ // (X >= 0) implies (X > C) when (C < 0)
+ if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
+ return getTrue(RetTy);
+ break;
+ case FCmpInst::FCMP_OEQ:
+ case FCmpInst::FCMP_OLE:
+ case FCmpInst::FCMP_OLT:
+ // (X >= 0) implies !(X < C) when (C < 0)
+ if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
+ return getFalse(RetTy);
+ break;
+ default:
+ break;
+ }
}
}