[llvm] 4fa54f8 - ConstantFolding: Fix handling of canonicalize for ppc_fp128 0s

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2022-12-13T08:44:20-05:00
New Revision: 4fa54f8b8196e83c7ab8856dab582387ce07282f

URL: https://github.com/llvm/llvm-project/commit/4fa54f8b8196e83c7ab8856dab582387ce07282f
DIFF: https://github.com/llvm/llvm-project/commit/4fa54f8b8196e83c7ab8856dab582387ce07282f.diff

LOG: ConstantFolding: Fix handling of canonicalize for ppc_fp128 0s

Added: 
    

Modified: 
    llvm/lib/Analysis/ConstantFolding.cpp
    llvm/test/Transforms/InstSimplify/canonicalize.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 71f3c57b610f7..9be7951c987b4 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1947,8 +1947,12 @@ getEvaluationRoundingMode(const ConstrainedFPIntrinsic *CI) {
 static Constant *constantFoldCanonicalize(const Type *Ty, const CallBase *CI,
                                           const APFloat &Src) {
   // Zero, positive and negative, is always OK to fold.
-  if (Src.isZero())
-    return ConstantFP::get(CI->getContext(), Src);
+  if (Src.isZero()) {
+    // Get a fresh 0, since ppc_fp128 does have non-canonical zeros.
+    return ConstantFP::get(
+        CI->getContext(),
+        APFloat::getZero(Src.getSemantics(), Src.isNegative()));
+  }
 
   if (!Ty->isIEEELikeFPTy())
     return nullptr;

diff  --git a/llvm/test/Transforms/InstSimplify/canonicalize.ll b/llvm/test/Transforms/InstSimplify/canonicalize.ll
index 2c7c402ec41a7..c14cd3b5e7292 100644
--- a/llvm/test/Transforms/InstSimplify/canonicalize.ll
+++ b/llvm/test/Transforms/InstSimplify/canonicalize.ll
@@ -593,6 +593,30 @@ define ppc_fp128 @canonicalize_negzero_ppcf128() {
   ret ppc_fp128 %ret
 }
 
+define ppc_fp128 @canonicalize_noncanonical_zero_0_ppcf128() {
+; CHECK-LABEL: @canonicalize_noncanonical_zero_0_ppcf128(
+; CHECK-NEXT:    ret ppc_fp128 0xM00000000000000000000000000000000
+;
+  %ret = call ppc_fp128 @llvm.canonicalize.ppcf128(ppc_fp128 0xM0000000000000000ffffffffffffffff)
+  ret ppc_fp128 %ret
+}
+
+define ppc_fp128 @canonicalize_noncanonical_zero_1_ppcf128() {
+; CHECK-LABEL: @canonicalize_noncanonical_zero_1_ppcf128(
+; CHECK-NEXT:    ret ppc_fp128 0xM00000000000000000000000000000000
+;
+  %ret = call ppc_fp128 @llvm.canonicalize.ppcf128(ppc_fp128 0xM00000000000000000000000000000001)
+  ret ppc_fp128 %ret
+}
+
+define ppc_fp128 @canonicalize_noncanonical_negzero_0_ppcf128() {
+; CHECK-LABEL: @canonicalize_noncanonical_negzero_0_ppcf128(
+; CHECK-NEXT:    ret ppc_fp128 0xM80000000000000000000000000000000
+;
+  %ret = call ppc_fp128 @llvm.canonicalize.ppcf128(ppc_fp128 0xM8000000000000000ffffffffffffffff)
+  ret ppc_fp128 %ret
+}
+
 define ppc_fp128 @canonicalize_inf_ppcf128() {
 ; CHECK-LABEL: @canonicalize_inf_ppcf128(
 ; CHECK-NEXT:    [[RET:%.*]] = call ppc_fp128 @llvm.canonicalize.ppcf128(ppc_fp128 0xM7FF00000000000000000000000000000)