[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

1 files changed, 25 insertions, 30 deletions

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);
         }
       }
       }