[PATCH] D147939: ValueTracking: Handle fptrunc in computeKnownFPClass

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: jcranmer-intel, kpn, cameron.mcinally, sepavloff, nikic, andrew.w.kaylor, scanon.
Herald added subscribers: StephenFan, okura, kuter, hiraditya.
Herald added a project: All.
arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a reviewer: jdoerfert.
Herald added a reviewer: sstefan1.
Herald added a project: LLVM.

This is the same as isKnownNeverNaN.


https://reviews.llvm.org/D147939

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll


Index: llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
===================================================================
--- llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
+++ llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
@@ -12,7 +12,7 @@
 }
 
 define float @ret_fptrunc_nonan(double nofpclass(nan) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_nonan
+; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_nonan
 ; CHECK-SAME: (double nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -102,7 +102,7 @@
 }
 
 define float @ret_fptrunc_nonan_noinf(double nofpclass(nan inf) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_nonan_noinf
+; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_nonan_noinf
 ; CHECK-SAME: (double nofpclass(nan inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4619,6 +4619,14 @@
       Known.SignBit = std::nullopt;
     break;
   }
+  case Instruction::FPTrunc: {
+    KnownFPClass KnownSrc;
+    computeKnownFPClass(Op->getOperand(0), DemandedElts,
+                        InterestedClasses, KnownSrc, Depth + 1, Q, TLI);
+    if (KnownSrc.isKnownNeverNaN())
+      Known.knownNot(fcNan);
+    break;
+  }
   case Instruction::SIToFP:
   case Instruction::UIToFP: {
     // Cannot produce nan


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D147939.512137.patch
Type: text/x-patch
Size: 1629 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230410/f8db448f/attachment.bin>