[llvm] r266452 - [InstCombine] Don't transform compares of calls to functions named fabs{f, l, }

[David Majnemer via llvm-commits]

Author: majnemer
Date: Fri Apr 15 12:21:03 2016
New Revision: 266452

URL: http://llvm.org/viewvc/llvm-project?rev=266452&view=rev
Log:
[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.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
    llvm/trunk/test/Transforms/InstCombine/pr27332.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=266452&r1=266451&r2=266452&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Fri Apr 15 12:21:03 2016
@@ -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
           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);
         }
       }
       }

Modified: llvm/trunk/test/Transforms/InstCombine/pr27332.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/pr27332.ll?rev=266452&r1=266451&r2=266452&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/pr27332.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/pr27332.ll Fri Apr 15 12:21:03 2016
@@ -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]]