[PATCH] D99207: [ValueTracking] Teach canCreateUndefOrPoison that ctpop does not create undef or poison.

[Craig Topper 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 rG4c38c35c8d84: [ValueTracking] Teach canCreateUndefOrPoison that ctpop does not create undef… (authored by craig.topper).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99207/new/

https://reviews.llvm.org/D99207

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/InstSimplify/select.ll


Index: llvm/test/Transforms/InstSimplify/select.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/select.ll
+++ llvm/test/Transforms/InstSimplify/select.ll
@@ -1015,6 +1015,20 @@
   ret i32 %sel
 }
 
+define i32 @select_ctpop_zero(i32 %x) {
+; CHECK-LABEL: @select_ctpop_zero(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = call i32 @llvm.ctpop.i32(i32 [[X:%.*]])
+; CHECK-NEXT:    ret i32 [[TMP0]]
+;
+entry:
+  %0 = icmp eq i32 %x, 0
+  %1 = call i32 @llvm.ctpop.i32(i32 %x)
+  %sel = select i1 %0, i32 0, i32 %1
+  ret i32 %sel
+}
+declare i32 @llvm.ctpop.i32(i32)
+
 ; TODO: these can be optimized more
 
 define i32 @poison(i32 %x, i32 %y) {
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4794,6 +4794,14 @@
     // destination type.
     return true;
   case Instruction::Call:
+    if (auto *II = dyn_cast<IntrinsicInst>(Op)) {
+      switch (II->getIntrinsicID()) {
+      // TODO: Add more intrinsics.
+      case Intrinsic::ctpop:
+        return false;
+      }
+    }
+    LLVM_FALLTHROUGH;
   case Instruction::CallBr:
   case Instruction::Invoke: {
     const auto *CB = cast<CallBase>(Op);


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