From 2e02ba78d5987592b110aa0b83c368262ccda17c Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Fri, 15 Apr 2016 17:21:03 +0000
Subject: [InstCombine] Don't transform compares of calls to functions named
 fabs{f,l,}

InstCombine wants to optimize compares of calls to fabs with zero.
However, we didn't have the necessary legality checking to verify that
the function call had the same behavior as fabs.

llvm-svn: 266452
---
 .../Transforms/InstCombine/InstCombineCompares.cpp | 55 ++++++++++------------
 1 file changed, 25 insertions(+), 30 deletions(-)

(limited to 'llvm/lib/Transforms/InstCombine')

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index c97b67eff24..013548ae4d2 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/VectorUtils.h"
 
 using namespace llvm;
 using namespace PatternMatch;
@@ -4564,39 +4565,33 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
           break;
 
         CallInst *CI = cast<CallInst>(LHSI);
-        const Function *F = CI->getCalledFunction();
-        if (!F)
+        Intrinsic::ID IID = getIntrinsicIDForCall(CI, TLI);
+        if (IID != Intrinsic::fabs)
           break;
 
         // Various optimization for fabs compared with zero.
-        LibFunc::Func Func;
-        if (F->getIntrinsicID() == Intrinsic::fabs ||
-            (TLI->getLibFunc(F->getName(), Func) && TLI->has(Func) &&
-             (Func == LibFunc::fabs || Func == LibFunc::fabsf ||
-              Func == LibFunc::fabsl))) {
-          switch (I.getPredicate()) {
-          default:
-            break;
-            // fabs(x) < 0 --> false
-          case FCmpInst::FCMP_OLT:
-            llvm_unreachable("handled by SimplifyFCmpInst");
-            // fabs(x) > 0 --> x != 0
-          case FCmpInst::FCMP_OGT:
-            return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), RHSC);
-            // fabs(x) <= 0 --> x == 0
-          case FCmpInst::FCMP_OLE:
-            return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), RHSC);
-            // fabs(x) >= 0 --> !isnan(x)
-          case FCmpInst::FCMP_OGE:
-            return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), RHSC);
-            // fabs(x) == 0 --> x == 0
-            // fabs(x) != 0 --> x != 0
-          case FCmpInst::FCMP_OEQ:
-          case FCmpInst::FCMP_UEQ:
-          case FCmpInst::FCMP_ONE:
-          case FCmpInst::FCMP_UNE:
-            return new FCmpInst(I.getPredicate(), CI->getArgOperand(0), RHSC);
-          }
+        switch (I.getPredicate()) {
+        default:
+          break;
+        // fabs(x) < 0 --> false
+        case FCmpInst::FCMP_OLT:
+          llvm_unreachable("handled by SimplifyFCmpInst");
+        // fabs(x) > 0 --> x != 0
+        case FCmpInst::FCMP_OGT:
+          return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), RHSC);
+        // fabs(x) <= 0 --> x == 0
+        case FCmpInst::FCMP_OLE:
+          return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), RHSC);
+        // fabs(x) >= 0 --> !isnan(x)
+        case FCmpInst::FCMP_OGE:
+          return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), RHSC);
+        // fabs(x) == 0 --> x == 0
+        // fabs(x) != 0 --> x != 0
+        case FCmpInst::FCMP_OEQ:
+        case FCmpInst::FCMP_UEQ:
+        case FCmpInst::FCMP_ONE:
+        case FCmpInst::FCMP_UNE:
+          return new FCmpInst(I.getPredicate(), CI->getArgOperand(0), RHSC);
         }
       }
       }
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