[PATCH] D128217: [ValueTracking] Teach isKnownNonZero that a vscale is never 0.

[Dave Green via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGbd1a4c8565ac: [ValueTracking] Teach isKnownNonZero that a vscale is never 0. (authored by dmgreen).

Changed prior to commit:
  https://reviews.llvm.org/D128217?vs=438439&id=439391#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D128217/new/

https://reviews.llvm.org/D128217

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/InstCombine/vscale_zero.ll


Index: llvm/test/Transforms/InstCombine/vscale_zero.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/vscale_zero.ll
@@ -0,0 +1,26 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i1 @iszero() {
+; CHECK-LABEL: @iszero(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i1 false
+;
+  entry:
+  %0 = call i32 @llvm.vscale.i32()
+  %1 = icmp eq i32 %0, 0
+  ret i1 %1
+}
+
+define i1 @iszero_range() vscale_range(1,16) {
+; CHECK-LABEL: @iszero_range(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i1 false
+;
+  entry:
+  %0 = call i32 @llvm.vscale.i32()
+  %1 = icmp eq i32 %0, 0
+  ret i1 %1
+}
+
+declare i32 @llvm.vscale.i32()
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -2698,6 +2698,9 @@
     if (isKnownNonZero(Op, Depth, Q) &&
         isGuaranteedNotToBePoison(Op, Q.AC, Q.CxtI, Q.DT, Depth))
       return true;
+  } else if (const auto *II = dyn_cast<IntrinsicInst>(V)) {
+    if (II->getIntrinsicID() == Intrinsic::vscale)
+      return true;
   }
 
   KnownBits Known(BitWidth);


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