[PATCH] D119643: [Transforms] Enhance CorrelatedValuePropagation to handle both values of select

[Dmitry Vassiliev via Phabricator via llvm-commits]

slydiman updated this revision to Diff 408410.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D119643/new/

https://reviews.llvm.org/D119643

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


Index: llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
===================================================================
--- llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
+++ llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
@@ -143,6 +143,66 @@
   ret void
 }
 
+; "false" case for CorrelatedValuePropagation
+define void @loop1(i32* %x, i32* %y) {
+; CHECK-LABEL: @loop1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:  loop:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32* [ [[F:%.*]], [[LOOP]] ], [ [[X:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[F]] = tail call i32* @f(i32* [[PHI]])
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ne i32* [[F]], [[Y:%.*]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP1]], i32* [[F]], i32* null
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq i32* [[SEL]], null
+; CHECK-NEXT:    br i1 [[CMP2]], label [[RETURN:%.*]], label [[LOOP]]
+; CHECK:       return:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+
+loop:
+	%phi = phi i32* [ %sel, %loop ], [ %x, %entry ]
+	%f = tail call i32* @f(i32* %phi)
+	%cmp1 = icmp ne i32* %f, %y
+	%sel = select i1 %cmp1, i32* %f, i32* null
+	%cmp2 = icmp eq i32* %sel, null
+	br i1 %cmp2, label %return, label %loop
+
+return:
+  ret void
+}
+
+; "true" case for CorrelatedValuePropagation
+define void @loop2(i32* %x, i32* %y) {
+; CHECK-LABEL: @loop2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32* [ [[F:%.*]], [[LOOP]] ], [ [[X:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[F]] = tail call i32* @f(i32* [[PHI]])
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i32* [[F]], [[Y:%.*]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP1]], i32* null, i32* [[F]]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq i32* [[SEL]], null
+; CHECK-NEXT:    br i1 [[CMP2]], label [[RETURN:%.*]], label [[LOOP]]
+; CHECK:       return:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+
+loop:
+	%phi = phi i32* [ %sel, %loop ], [ %x, %entry ]
+	%f = tail call i32* @f(i32* %phi)
+	%cmp1 = icmp eq i32* %f, %y
+	%sel = select i1 %cmp1, i32* null, i32* %f
+	%cmp2 = icmp eq i32* %sel, null
+	br i1 %cmp2, label %return, label %loop
+
+return:
+  ret void
+}
+
 define i32 @switch1(i32 %s) {
 ; CHECK-LABEL: @switch1(
 ; CHECK-NEXT:  entry:
Index: llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -245,11 +245,20 @@
   // value can never be that constant. In that case replace the incoming
   // value with the other value of the select. This often allows us to
   // remove the select later.
+
+  // The "false" case
   if (auto *C = dyn_cast<Constant>(SI->getFalseValue()))
     if (LVI->getPredicateOnEdge(ICmpInst::ICMP_EQ, SI, C, From, To, CxtI) ==
         LazyValueInfo::False)
       return SI->getTrueValue();
 
+  // The "true" case,
+  // similar to the select "false" case, but try the select "true" value
+  if (auto *C = dyn_cast<Constant>(SI->getTrueValue()))
+    if (LVI->getPredicateOnEdge(ICmpInst::ICMP_EQ, SI, C, From, To, CxtI) ==
+        LazyValueInfo::False)
+      return SI->getFalseValue();
+
   return nullptr;
 }
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D119643.408410.patch
Type: text/x-patch
Size: 3316 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220214/b4fa1bb2/attachment.bin>