[llvm] [MachineCopyPropagation] When the source of PreviousCopy is undef, we cannot replace sub register (PR #74682)
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Thu Dec 7 06:56:25 PST 2023
https://github.com/DianQK updated https://github.com/llvm/llvm-project/pull/74682
>From efbd7f1b6022d194bc91302667d8850504cf0df0 Mon Sep 17 00:00:00 2001
From: DianQK <dianqk at dianqk.net>
Date: Thu, 7 Dec 2023 22:40:33 +0800
Subject: [PATCH] [MachineCopyPropagation] Pre-commit test case
---
llvm/lib/CodeGen/MachineCopyPropagation.cpp | 3 ++
.../test/CodeGen/AArch64/machine-cp-undef.mir | 33 +++++++++++++++++++
2 files changed, 36 insertions(+)
create mode 100644 llvm/test/CodeGen/AArch64/machine-cp-undef.mir
diff --git a/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
index a032b31a1fc7c..fdbdaa0a6d641 100644
--- a/llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -443,6 +443,9 @@ static bool isNopCopy(const MachineInstr &PreviousCopy, MCRegister Src,
return true;
if (!TRI->isSubRegister(PreviousSrc, Src))
return false;
+ // When the source of PreviousCopy is undef, we cannot replace sub register.
+ if (CopyOperands->Source->isUndef())
+ return false;
unsigned SubIdx = TRI->getSubRegIndex(PreviousSrc, Src);
return SubIdx == TRI->getSubRegIndex(PreviousDef, Def);
}
diff --git a/llvm/test/CodeGen/AArch64/machine-cp-undef.mir b/llvm/test/CodeGen/AArch64/machine-cp-undef.mir
new file mode 100644
index 0000000000000..6c09f2ce7fcc1
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/machine-cp-undef.mir
@@ -0,0 +1,33 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
+# RUN: llc -o - %s -O3 --run-pass=machine-cp -mcp-use-is-copy-instr -mtriple=arm64-apple-macos -mcpu=apple-m1 --verify-machineinstrs | FileCheck %s
+
+---
+name: test
+tracksRegLiveness: true
+body: |
+ ; CHECK-LABEL: name: test
+ ; CHECK: bb.0:
+ ; CHECK-NEXT: successors: %bb.1(0x80000000)
+ ; CHECK-NEXT: liveins: $w0
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: $x8 = ORRXrs $xzr, undef $x0, 0, implicit $w0
+ ; CHECK-NEXT: $w8 = ORRWrs $wzr, $w0, 0, implicit-def $x8
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: bb.1:
+ ; CHECK-NEXT: liveins: $x8
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: $x0 = ADDXri $x8, 1, 0
+ ; CHECK-NEXT: RET undef $lr, implicit $x0
+ bb.0:
+ successors: %bb.1(0x80000000)
+ liveins: $w0
+
+ $x8 = ORRXrs $xzr, undef $x0, 0, implicit $w0
+ $w8 = ORRWrs $wzr, $w0, 0, implicit-def $x8
+
+ bb.1:
+ liveins: $x8
+ $x0 = ADDXri $x8, 1, 0
+
+ RET undef $lr, implicit $x0
+...
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