From 69c8972fd1dd4beb75421dd32110d2f0e1cb3a5f Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Mon, 26 Feb 2018 22:33:17 +0000
Subject: [PATCH] [ValueTracking] Teach cannotBeOrderedLessThanZeroImpl to
 handle vector constants.

Summary: This allows vector fabs to be removed in more cases.

Reviewers: spatel, arsenm, RKSimon

Reviewed By: spatel

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D43739

llvm-svn: 326138
---
 llvm/lib/Analysis/ValueTracking.cpp                    | 18 ++++++++++++++++++
 .../InstSimplify/floating-point-arithmetic.ll          |  6 ++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index e425599..a1ec9df 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2728,6 +2728,24 @@ static bool cannotBeOrderedLessThanZeroImpl(const Value *V,
            (!SignBitOnly && CFP->getValueAPF().isZero());
   }
 
+  // Handle vector of constants.
+  if (auto *CV = dyn_cast<Constant>(V)) {
+    if (CV->getType()->isVectorTy()) {
+      unsigned NumElts = CV->getType()->getVectorNumElements();
+      for (unsigned i = 0; i != NumElts; ++i) {
+        auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
+        if (!CFP)
+          return false;
+        if (CFP->getValueAPF().isNegative() &&
+            (SignBitOnly || !CFP->getValueAPF().isZero()))
+          return false;
+      }
+
+      // All non-negative ConstantFPs.
+      return true;
+    }
+  }
+
   if (Depth == MaxDepth)
     return false; // Limit search depth.
 
diff --git a/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
index 5ec820f..ba177ea 100644
--- a/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
+++ b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
@@ -132,8 +132,7 @@ define <2 x float> @fabs_select_positive_constants_vector(i32 %c) {
 ; CHECK-LABEL: @fabs_select_positive_constants_vector(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[C:%.*]], 0
 ; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP]], <2 x float> <float 1.000000e+00, float 1.000000e+00>, <2 x float> <float 2.000000e+00, float 2.000000e+00>
-; CHECK-NEXT:    [[FABS:%.*]] = call <2 x float> @llvm.fabs.v2f32(<2 x float> [[SELECT]])
-; CHECK-NEXT:    ret <2 x float> [[FABS]]
+; CHECK-NEXT:    ret <2 x float> [[SELECT]]
 ;
   %cmp = icmp eq i32 %c, 0
   %select = select i1 %cmp, <2 x float> <float 1.0, float 1.0>, <2 x float> <float 2.0, float 2.0>
@@ -235,8 +234,7 @@ define <2 x float> @fabs_select_nan_nan_vector(i32 %c) {
 ; CHECK-LABEL: @fabs_select_nan_nan_vector(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[C:%.*]], 0
 ; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP]], <2 x float> <float 0x7FF8000000000000, float 0x7FF8000000000000>, <2 x float> <float 0x7FF8000100000000, float 0x7FF8000100000000>
-; CHECK-NEXT:    [[FABS:%.*]] = call <2 x float> @llvm.fabs.v2f32(<2 x float> [[SELECT]])
-; CHECK-NEXT:    ret <2 x float> [[FABS]]
+; CHECK-NEXT:    ret <2 x float> [[SELECT]]
 ;
   %cmp = icmp eq i32 %c, 0
   %select = select i1 %cmp, <2 x float> <float 0x7FF8000000000000, float 0x7FF8000000000000>, <2 x float> <float 0x7FF8000100000000, float 0x7FF8000100000000>
-- 
2.7.4