[RegAlloc] Fix the terminal rule check for interfere with DstReg #168661
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@llvm/pr-subscribers-backend-x86 @llvm/pr-subscribers-llvm-regalloc Author: None (hstk30-hw) ChangesThis maybe a bug which is introduced by commit 6749ae3, and has been present ever since. Full diff: https://github.com/llvm/llvm-project/pull/168661.diff 1 Files Affected:
diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp
index 25c4375a73ce0..e624088a0964e 100644
--- a/llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -4150,7 +4150,7 @@ bool RegisterCoalescer::applyTerminalRule(const MachineInstr &Copy) const {
continue;
Register OtherSrcReg, OtherReg;
unsigned OtherSrcSubReg = 0, OtherSubReg = 0;
- if (!isMoveInstr(*TRI, &Copy, OtherSrcReg, OtherReg, OtherSrcSubReg,
+ if (!isMoveInstr(*TRI, &MI, OtherSrcReg, OtherReg, OtherSrcSubReg,
OtherSubReg))
return false;
if (OtherReg == SrcReg)
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Contributor
Author
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There are many testcases fail, so if this is right, then I will fix and update it. |
Contributor
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The fix looks intuitively correct to me |
qcolombet
reviewed
Nov 19, 2025
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qcolombet
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Great catch @hstk30-hw!
Do you have a test case that exercises this problem.
Contributor
Author
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Fix all failed testcase. |
arsenm
approved these changes
Nov 20, 2025
🐧 Linux x64 Test Results
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Contributor
Author
Not for now :) I see luke get a nice performance improvement on MiBench with a 17% reduction in dynamic instruction count. |
Contributor
I think @qcolombet meant a mir lit test which shows the change, not benchmark results |
Collaborator
Yes, that's what I meant :). |
qcolombet
approved these changes
Nov 21, 2025
Contributor
Author
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Merge first. I will provide a mir testcase later. |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/162/builds/35751 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/140/builds/34552 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/108/builds/20129 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/85/builds/15978 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/55/builds/20497 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/94/builds/12954 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/169/builds/17363 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/164/builds/15939 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/24/builds/15003 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/145/builds/11023 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/25/builds/13483 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/202/builds/4304 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/52/builds/13063 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/110/builds/6452 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/42/builds/7085 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/136/builds/6048 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/87/builds/4263 Here is the relevant piece of the build log for the reference |
Contributor
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I've reverted this due to the bot failures in d5f3ab8. Sorry for the inconvenience. |
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Nov 23, 2025
…Reg (llvm#168661)" Fix failed testcase.
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…Reg (llvm#168661)" This reverts commit 0859ac5. This caused a couple test failures, likely due to a mid-air collision. Reverting for now to get the tree back to green and allow the original author to run UTC/friends and verify the output.
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…Reg (llvm#168661)" (llvm#169219) Reland d5f3ab8, fix testcases.
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…Reg (llvm#168661)" This reverts commit 0859ac5. This caused a couple test failures, likely due to a mid-air collision. Reverting for now to get the tree back to green and allow the original author to run UTC/friends and verify the output.
Priyanshu3820
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…Reg (llvm#168661)" (llvm#169219) Reland d5f3ab8, fix testcases.
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augusto2112
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…Reg (llvm#168661)" This reverts commit 0859ac5. This caused a couple test failures, likely due to a mid-air collision. Reverting for now to get the tree back to green and allow the original author to run UTC/friends and verify the output.
augusto2112
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…Reg (llvm#168661)" (llvm#169219) Reland d5f3ab8, fix testcases.
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This maybe a bug which is introduced by commit 6749ae3, and has been present ever since.
In this case,
OtherRegalways overlaps withDstRegcause they from theCopyall.