[PATCH] D50247: [GuardWidening] Ignore guards with trivial conditions

[Max Kazantsev via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL340381: [GuardWidening] Ignore guards with trivial conditions (authored by mkazantsev, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D50247?vs=158986&id=161880#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D50247

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


Index: llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp
+++ llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp
@@ -347,6 +347,12 @@
     Instruction *GuardInst, const df_iterator<DomTreeNode *> &DFSI,
     const DenseMap<BasicBlock *, SmallVector<Instruction *, 8>> &
         GuardsInBlock, bool InvertCondition) {
+  // Ignore trivial true or false conditions. These instructions will be
+  // trivially eliminated by any cleanup pass. Do not erase them because other
+  // guards can possibly be widened into them.
+  if (isa<ConstantInt>(getCondition(GuardInst)))
+    return false;
+
   Instruction *BestSoFar = nullptr;
   auto BestScoreSoFar = WS_IllegalOrNegative;
   auto *GuardInstLoop = LI.getLoopFor(GuardInst->getParent());
Index: llvm/trunk/test/Transforms/GuardWidening/basic.ll
===================================================================
--- llvm/trunk/test/Transforms/GuardWidening/basic.ll
+++ llvm/trunk/test/Transforms/GuardWidening/basic.ll
@@ -379,3 +379,29 @@
 right:
   ret void
 }
+
+; Make sure we do not widen guard by trivial true conditions into something.
+define void @f_15(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_15(
+entry:
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 true) [ "deopt"() ]
+; CHECK:  ret void
+
+  call void(i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+  call void(i1, ...) @llvm.experimental.guard(i1 true) [ "deopt"() ]
+  ret void
+}
+
+; Make sure we do not widen guard by trivial false conditions into something.
+define void @f_16(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_16(
+entry:
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 false) [ "deopt"() ]
+; CHECK:  ret void
+
+  call void(i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+  call void(i1, ...) @llvm.experimental.guard(i1 false) [ "deopt"() ]
+  ret void
+}


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