[PATCH] D72169: [CVP] Simplify cmp of local phi node

[Nikita Popov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG9d9633fb700d: [CVP] Simplify cmp of local phi node (authored by nikic).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D72169/new/

https://reviews.llvm.org/D72169

Files:
  llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
  llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll


Index: llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
===================================================================
--- llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
+++ llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -627,11 +627,9 @@
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[P:%.*]] = phi i8 [ [[A]], [[ENTRY:%.*]] ], [ [[B:%.*]], [[LOOP]] ]
 ; CHECK-NEXT:    [[C1:%.*]] = icmp ne i8 [[P]], 0
-; CHECK-NEXT:    [[C2:%.*]] = icmp ne i8 [[P]], 2
-; CHECK-NEXT:    [[C3:%.*]] = and i1 [[C1]], [[C2]]
 ; CHECK-NEXT:    [[C4:%.*]] = call i1 @get_bool()
 ; CHECK-NEXT:    [[B]] = zext i1 [[C4]] to i8
-; CHECK-NEXT:    br i1 [[C3]], label [[LOOP]], label [[EXIT]]
+; CHECK-NEXT:    br i1 [[C1]], label [[LOOP]], label [[EXIT]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
 ;
Index: llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -310,9 +310,10 @@
   // the comparison is testing local values.  While LVI can sometimes reason
   // about such cases, it's not its primary purpose.  We do make sure to do
   // the block local query for uses from terminator instructions, but that's
-  // handled in the code for each terminator.
+  // handled in the code for each terminator. As an exception, we allow phi
+  // nodes, for which LVI can thread the condition into predecessors.
   auto *I = dyn_cast<Instruction>(Op0);
-  if (I && I->getParent() == Cmp->getParent())
+  if (I && I->getParent() == Cmp->getParent() && !isa<PHINode>(I))
     return false;
 
   LazyValueInfo::Tristate Result =


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D72169.246804.patch
Type: text/x-patch
Size: 1732 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200226/586c7eb2/attachment.bin>