[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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266452 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index c97b67e..013548a 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/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);
         }
       }
       }

diff --git a/test/Transforms/InstCombine/pr27332.ll b/test/Transforms/InstCombine/pr27332.ll
index 543ffbe..87e440e 100644 (file)
--- a/test/Transforms/InstCombine/pr27332.ll
+++ b/test/Transforms/InstCombine/pr27332.ll
@@ -9,3 +9,15 @@ entry:
 }
 ; CHECK-LABEL: define <4 x i1> @test1(
 ; CHECK:   ret <4 x i1> zeroinitializer
+
+declare float @fabsf()
+
+define i1 @test2() {
+  %call = call float @fabsf()
+  %cmp = fcmp olt float %call, 0.000000e+00
+  ret i1 %cmp
+}
+; CHECK-LABEL: define i1 @test2(
+; CHECK:  %[[call:.*]] = call float @fabsf()
+; CHECK:  %[[cmp:.*]] = fcmp olt float %[[call]], 0.000000e+00
+; CHECK:  ret i1 %[[cmp]]