[PATCH] D158014: [LLVM][Uniformity] Fix error causing assert on some irreducible control flow
Sameer Sahasrabuddhe via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 17 21:18:59 PDT 2023
This revision was automatically updated to reflect the committed changes.
Closed by commit rG09e12d13a04f: [LLVM][Uniformity] Fix error causing assert on some irreducible control flow (authored by AlexM, committed by sameerds).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D158014/new/
https://reviews.llvm.org/D158014
Files:
llvm/include/llvm/ADT/GenericUniformityImpl.h
llvm/test/Analysis/UniformityAnalysis/NVPTX/non-header-join.ll
Index: llvm/test/Analysis/UniformityAnalysis/NVPTX/non-header-join.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/UniformityAnalysis/NVPTX/non-header-join.ll
@@ -0,0 +1,24 @@
+; RUN: opt %s -passes='print<uniformity>' -disable-output 2>&1 | FileCheck %s
+
+target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
+target triple = "nvptx64-nvidia-cuda"
+
+; CHECK: CYCLES ASSSUMED DIVERGENT:
+; CHECK-NEXT: depth=1: entries(if.end16 for.cond1) for.body4
+
+define void @foo(i1 %b) {
+entry:
+ br i1 %b, label %if.then, label %if.end16
+
+if.then: ; preds = %entry
+ br label %for.cond1
+
+for.cond1: ; preds = %if.end16, %for.body4, %if.then
+ br i1 false, label %for.body4, label %if.end16
+
+for.body4: ; preds = %for.cond1
+ br label %for.cond1
+
+if.end16: ; preds = %for.cond1, %entry
+ br label %for.cond1
+}
Index: llvm/include/llvm/ADT/GenericUniformityImpl.h
===================================================================
--- llvm/include/llvm/ADT/GenericUniformityImpl.h
+++ llvm/include/llvm/ADT/GenericUniformityImpl.h
@@ -946,11 +946,6 @@
if (Cycle->contains(DivTermBlock))
return nullptr;
- if (Cycle->isReducible()) {
- assert(Cycle->getHeader() == JoinBlock);
- return nullptr;
- }
-
const auto *Parent = Cycle->getParentCycle();
while (Parent && !Parent->contains(DivTermBlock)) {
// If the join is inside a child, then the parent must be
@@ -961,6 +956,11 @@
Parent = Cycle->getParentCycle();
}
+ if (Cycle->isReducible()) {
+ assert(Cycle->getHeader() == JoinBlock);
+ return nullptr;
+ }
+
LLVM_DEBUG(dbgs() << "cycle made divergent by external branch\n");
return Cycle;
}
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