[PATCH] D136097: InstSimplify: Fold fdiv nnan nsz x, 0 -> inf

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: spatel, kpn, cameron.mcinally.
Herald added a subscriber: hiraditya.
Herald added a project: All.
arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

https://reviews.llvm.org/D136097

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/test/Transforms/InstSimplify/fdiv.ll


Index: llvm/test/Transforms/InstSimplify/fdiv.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/fdiv.ll
+++ llvm/test/Transforms/InstSimplify/fdiv.ll
@@ -121,8 +121,7 @@
 ; https://alive2.llvm.org/ce/z/ryZBn6
 define float @fdiv_nnan_nsz_ninf_by_zero_f32(float %x) {
 ; CHECK-LABEL: @fdiv_nnan_nsz_ninf_by_zero_f32(
-; CHECK-NEXT:    [[FDIV:%.*]] = fdiv nnan nsz float [[X:%.*]], 0.000000e+00
-; CHECK-NEXT:    ret float [[FDIV]]
+; CHECK-NEXT:    ret float 0x7FF0000000000000
 ;
   %fdiv = fdiv nnan nsz float %x, 0.0
   ret float %fdiv
@@ -130,8 +129,7 @@
 
 define float @fdiv_nnan_nsz_ninf_by_negzero_f32(float %x) {
 ; CHECK-LABEL: @fdiv_nnan_nsz_ninf_by_negzero_f32(
-; CHECK-NEXT:    [[FDIV:%.*]] = fdiv nnan nsz float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    ret float [[FDIV]]
+; CHECK-NEXT:    ret float 0x7FF0000000000000
 ;
   %fdiv = fdiv nnan nsz float %x, -0.0
   ret float %fdiv
@@ -139,8 +137,7 @@
 
 define <2 x float> @fdiv_nnan_nsz_ninf_by_zero_v2f32(<2 x float> %x) {
 ; CHECK-LABEL: @fdiv_nnan_nsz_ninf_by_zero_v2f32(
-; CHECK-NEXT:    [[FDIV:%.*]] = fdiv nnan nsz <2 x float> [[X:%.*]], zeroinitializer
-; CHECK-NEXT:    ret <2 x float> [[FDIV]]
+; CHECK-NEXT:    ret <2 x float> <float 0x7FF0000000000000, float 0x7FF0000000000000>
 ;
   %fdiv = fdiv nnan nsz <2 x float> %x, zeroinitializer
   ret <2 x float> %fdiv
@@ -148,8 +145,7 @@
 
 define <2 x float> @fdiv_nnan_nsz_ninf_by_negzero_v2f32(<2 x float> %x) {
 ; CHECK-LABEL: @fdiv_nnan_nsz_ninf_by_negzero_v2f32(
-; CHECK-NEXT:    [[FDIV:%.*]] = fdiv nnan nsz <2 x float> [[X:%.*]], <float -0.000000e+00, float -0.000000e+00>
-; CHECK-NEXT:    ret <2 x float> [[FDIV]]
+; CHECK-NEXT:    ret <2 x float> <float 0x7FF0000000000000, float 0x7FF0000000000000>
 ;
   %fdiv = fdiv nnan nsz <2 x float> %x, <float -0.0, float -0.0>
   ret <2 x float> %fdiv
Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5448,6 +5448,10 @@
     // nnan ninf X / 0.0 -> poison
     if (FMF.noInfs() && match(Op1, m_AnyZeroFP()))
       return PoisonValue::get(Op1->getType());
+
+    // nnan nsz X / 0.0 -> inf
+    if (FMF.noSignedZeros() && match(Op1, m_AnyZeroFP()))
+      return ConstantFP::getInfinity(Op1->getType());
   }
 
   return nullptr;


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