From d4dc30c20d0f82ba3b4691f5edb71626b3ff799b Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Wed, 31 Oct 2018 15:35:46 +0000
Subject: [PATCH] [InstSimplify] fold 'fcmp nnan ult X, 0.0' when X is not
 negative

This is the inverted case for the transform added with D53874 / rL345725.

llvm-svn: 345728
---
 llvm/lib/Analysis/InstructionSimplify.cpp        |  5 ++++-
 .../InstSimplify/floating-point-compare.ll       | 16 ++++------------
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index efe88507aefb..8571dc2cf2fc 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3620,8 +3620,11 @@ static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
         if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
           return getTrue(RetTy);
         break;
+      case FCmpInst::FCMP_ULT:
+        if (FMF.noNaNs() && CannotBeOrderedLessThanZero(LHS, Q.TLI))
+          return getFalse(RetTy);
+        break;
       case FCmpInst::FCMP_OLT:
-        // X < 0
         if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
           return getFalse(RetTy);
         break;
diff --git a/llvm/test/Transforms/InstSimplify/floating-point-compare.ll b/llvm/test/Transforms/InstSimplify/floating-point-compare.ll
index 7df803edc688..14e6ccee7b27 100644
--- a/llvm/test/Transforms/InstSimplify/floating-point-compare.ll
+++ b/llvm/test/Transforms/InstSimplify/floating-point-compare.ll
@@ -290,9 +290,7 @@ define <2 x i1> @UIToFP_is_not_negative_vec(<2 x i32> %x) {
 
 define i1 @UIToFP_nnan_is_not_negative(i32 %x) {
 ; CHECK-LABEL: @UIToFP_nnan_is_not_negative(
-; CHECK-NEXT:    [[A:%.*]] = uitofp i32 [[X:%.*]] to float
-; CHECK-NEXT:    [[R:%.*]] = fcmp nnan ult float [[A]], 0.000000e+00
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 false
 ;
   %a = uitofp i32 %x to float
   %r = fcmp nnan ult float %a, 0.000000e+00
@@ -301,9 +299,7 @@ define i1 @UIToFP_nnan_is_not_negative(i32 %x) {
 
 define <2 x i1> @UIToFP_nnan_is_not_negative_vec(<2 x i32> %x) {
 ; CHECK-LABEL: @UIToFP_nnan_is_not_negative_vec(
-; CHECK-NEXT:    [[A:%.*]] = uitofp <2 x i32> [[X:%.*]] to <2 x float>
-; CHECK-NEXT:    [[R:%.*]] = fcmp nnan ult <2 x float> [[A]], zeroinitializer
-; CHECK-NEXT:    ret <2 x i1> [[R]]
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
 ;
   %a = uitofp <2 x i32> %x to <2 x float>
   %r = fcmp nnan ult <2 x float> %a, zeroinitializer
@@ -366,9 +362,7 @@ define <2 x i1> @fabs_is_not_negative_vec(<2 x double> %x) {
 
 define i1 @fabs_nnan_is_not_negative(double %x) {
 ; CHECK-LABEL: @fabs_nnan_is_not_negative(
-; CHECK-NEXT:    [[FABS:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
-; CHECK-NEXT:    [[CMP:%.*]] = fcmp nnan ult double [[FABS]], 0.000000e+00
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    ret i1 false
 ;
   %fabs = tail call double @llvm.fabs.f64(double %x)
   %cmp = fcmp nnan ult double %fabs, 0.0
@@ -377,9 +371,7 @@ define i1 @fabs_nnan_is_not_negative(double %x) {
 
 define <2 x i1> @fabs_nnan_is_not_negative_vec(<2 x double> %x) {
 ; CHECK-LABEL: @fabs_nnan_is_not_negative_vec(
-; CHECK-NEXT:    [[FABS:%.*]] = tail call <2 x double> @llvm.fabs.v2f64(<2 x double> [[X:%.*]])
-; CHECK-NEXT:    [[CMP:%.*]] = fcmp nnan ult <2 x double> [[FABS]], zeroinitializer
-; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
 ;
   %fabs = tail call <2 x double> @llvm.fabs.v2f64(<2 x double> %x)
   %cmp = fcmp nnan ult <2 x double> %fabs, zeroinitializer