[PATCH] D51595: [NewGVN] Update use counts for SSA copies when replacing them by their operands.
Florian Hahn via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 7 10:16:07 PST 2018
fhahn updated this revision to Diff 172980.
fhahn marked an inline comment as done.
fhahn added a comment.
use unsigned instead of auto
https://reviews.llvm.org/D51595
Files:
lib/Transforms/Scalar/NewGVN.cpp
test/Transforms/NewGVN/eliminate-ssacopy.ll
Index: test/Transforms/NewGVN/eliminate-ssacopy.ll
===================================================================
--- /dev/null
+++ test/Transforms/NewGVN/eliminate-ssacopy.ll
@@ -0,0 +1,50 @@
+; RUN: opt -newgvn -S < %s | FileCheck %s
+
+; Make sure the created ssa copies are cleaned up.
+
+; CHECK-NOT: ssa_copy
+
+ at b = external dso_local local_unnamed_addr global i32, align 4
+ at a = external dso_local local_unnamed_addr global i8, align 1
+ at f = external dso_local local_unnamed_addr global i16, align 2
+
+define void @g() {
+entry:
+ %tobool = icmp eq i32 undef, 0
+ br i1 %tobool, label %for.cond1thread-pre-split, label %for.cond.preheader
+
+for.cond.preheader: ; preds = %entry
+ unreachable
+
+for.cond1thread-pre-split: ; preds = %entry
+ br label %for.end4.split
+
+for.end4.split: ; preds = %for.cond1thread-pre-split
+ br i1 %tobool, label %for.cond6.preheader, label %if.end11
+
+for.cond6.preheader: ; preds = %for.end4.split
+ br i1 undef, label %for.cond6.preheader3, label %if.end11.loopexit
+
+for.cond6.preheader3: ; preds = %for.cond6.preheader
+ br label %if.end11.loopexit
+
+if.end11.loopexit: ; preds = %for.cond6.preheader3, %for.cond6.preheader
+ %storemerge.lcssa = phi i32 [ 0, %for.cond6.preheader ], [ 1, %for.cond6.preheader3 ]
+ store i32 %storemerge.lcssa, i32* @b, align 4
+ br label %if.end11
+
+if.end11: ; preds = %if.end11.loopexit, %for.end4.split
+ %0 = load i32, i32* @b, align 4
+ %1 = load i8, i8* @a, align 1
+ %conv = sext i8 %1 to i32
+ %cmp12 = icmp eq i32 %0, %conv
+ br i1 %cmp12, label %if.then14, label %if.end16
+
+if.then14: ; preds = %if.end11
+ %conv15 = trunc i32 %0 to i16
+ store i16 %conv15, i16* @f, align 2
+ unreachable
+
+if.end16: ; preds = %if.end11
+ ret void
+}
Index: lib/Transforms/Scalar/NewGVN.cpp
===================================================================
--- lib/Transforms/Scalar/NewGVN.cpp
+++ lib/Transforms/Scalar/NewGVN.cpp
@@ -4094,10 +4094,13 @@
// It's about to be alive again.
if (LeaderUseCount == 0 && isa<Instruction>(DominatingLeader))
ProbablyDead.erase(cast<Instruction>(DominatingLeader));
- // Copy instructions, however, are still dead because we use their
- // operand as the leader.
- if (LeaderUseCount == 0 && isSSACopy)
- ProbablyDead.insert(II);
+ // For copy instructions, we use their operand as a leader,
+ // which means we remove a user of the copy and it may become dead.
+ if (isSSACopy) {
+ unsigned &IIUseCount = UseCounts[II];
+ if (--IIUseCount == 0)
+ ProbablyDead.insert(II);
+ }
++LeaderUseCount;
AnythingReplaced = true;
}
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D51595.172980.patch
Type: text/x-patch
Size: 3040 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20181107/613ccf7d/attachment.bin>
More information about the llvm-commits
mailing list