[llvm-commits] [llvm] r162174 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineCompares.cpp test/Transforms/InstCombine/fcmp.ll

[Benjamin Kramer]

Author: d0k
Date: Sat Aug 18 15:06:47 2012
New Revision: 162174

URL: http://llvm.org/viewvc/llvm-project?rev=162174&view=rev
Log:
InstCombine: Add a couple of fabs identities for comparing with 0.0.

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

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=162174&r1=162173&r2=162174&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Sat Aug 18 15:06:47 2012
@@ -17,6 +17,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
 #include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Support/ConstantRange.h"
 #include "llvm/Support/GetElementPtrTypeIterator.h"
 #include "llvm/Support/PatternMatch.h"
@@ -2985,6 +2986,44 @@
                 return Res;
         }
         break;
+      case Instruction::Call: {
+        CallInst *CI = cast<CallInst>(LHSI);
+        LibFunc::Func Func;
+        // Various optimization for fabs compared with zero.
+        if (RHSC->isNullValue() && CI->hasOneUse() &&
+            TLI->getLibFunc(CI->getCalledFunction()->getName(), Func) &&
+            TLI->has(Func)) {
+          if (Func == LibFunc::fabs || Func == LibFunc::fabsf ||
+              Func == LibFunc::fabsl) {
+            switch (I.getPredicate()) {
+            default: break;
+            // fabs(x) < 0 --> false
+            case FCmpInst::FCMP_OLT:
+              return ReplaceInstUsesWith(I, Builder->getFalse());
+            // 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/fcmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fcmp.ll?rev=162174&r1=162173&r2=162174&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fcmp.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/fcmp.ll Sat Aug 18 15:06:47 2012
@@ -69,3 +69,85 @@
 ; CHECK: @test8
 ; CHECK-NEXT: fcmp olt float %x, 0.000000e+00
 }
+
+declare double @fabs(double) nounwind readnone
+
+define i32 @test9(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp olt double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test9
+; CHECK-NOT: fabs
+; CHECK: ret i32 0
+}
+
+define i32 @test10(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp ole double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test10
+; CHECK-NOT: fabs
+; CHECK: fcmp oeq double %a, 0.000000e+00
+}
+
+define i32 @test11(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp ogt double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test11
+; CHECK-NOT: fabs
+; CHECK: fcmp one double %a, 0.000000e+00
+}
+
+define i32 @test12(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp oge double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test12
+; CHECK-NOT: fabs
+; CHECK: fcmp ord double %a, 0.000000e+00
+}
+
+define i32 @test13(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp une double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test13
+; CHECK-NOT: fabs
+; CHECK: fcmp une double %a, 0.000000e+00
+}
+
+define i32 @test14(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp oeq double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test14
+; CHECK-NOT: fabs
+; CHECK: fcmp oeq double %a, 0.000000e+00
+}
+
+define i32 @test15(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp one double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test15
+; CHECK-NOT: fabs
+; CHECK: fcmp one double %a, 0.000000e+00
+}
+
+define i32 @test16(double %a) nounwind {
+  %call = tail call double @fabs(double %a) nounwind
+  %cmp = fcmp ueq double %call, 0.000000e+00
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+; CHECK: @test16
+; CHECK-NOT: fabs
+; CHECK: fcmp ueq double %a, 0.000000e+00
+}