[llvm] 24633ea - [Peephole] Check instructions from CopyMIs are still COPY (#69511)

[via llvm-commits]

Author: weiguozhi
Date: 2023-10-20T08:34:43-07:00
New Revision: 24633eac38d46cd4b253ba53258165ee08d886cd

URL: https://github.com/llvm/llvm-project/commit/24633eac38d46cd4b253ba53258165ee08d886cd
DIFF: https://github.com/llvm/llvm-project/commit/24633eac38d46cd4b253ba53258165ee08d886cd.diff

LOG: [Peephole] Check instructions from CopyMIs are still COPY (#69511)

Function foldRedundantCopy records COPY instructions in CopyMIs and uses
it later. But other optimizations may delete or modify it. So before
using it we should check if the extracted instruction is existing and
still a COPY instruction.

Added: 
    llvm/test/CodeGen/X86/peephole-copy.mir

Modified: 
    llvm/lib/CodeGen/PeepholeOptimizer.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/PeepholeOptimizer.cpp b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
index f413ca5b04f48cf..09ae2680f5516ba 100644
--- a/llvm/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
@@ -1445,7 +1445,9 @@ bool PeepholeOptimizer::foldRedundantCopy(
   }
 
   MachineInstr *PrevCopy = CopyMIs.find(SrcPair)->second;
-  if (!LocalMIs.count(PrevCopy))
+  // A COPY instruction can be deleted or changed by other optimizations.
+  // Check if the previous COPY instruction is existing and still a COPY.
+  if (!LocalMIs.count(PrevCopy) || !PrevCopy->isCopy())
     return false;
 
   assert(SrcSubReg == PrevCopy->getOperand(1).getSubReg() &&

diff  --git a/llvm/test/CodeGen/X86/peephole-copy.mir b/llvm/test/CodeGen/X86/peephole-copy.mir
new file mode 100644
index 000000000000000..e875465dfc9f972
--- /dev/null
+++ b/llvm/test/CodeGen/X86/peephole-copy.mir
@@ -0,0 +1,34 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 3
+# RUN: llc -mtriple=i686-- -run-pass=peephole-opt %s -o - | FileCheck %s
+--- |
+  define void @c() {
+  entry:
+    tail call void asm sideeffect "", "q,~{dirflag},~{fpsr},~{flags}"(i32 512)
+    tail call void asm sideeffect "", "q,~{dirflag},~{fpsr},~{flags}"(i32 512)
+    ret void
+  }
+...
+---
+# In peephole optimization the modified COPY instruction should not cause
+# compiler failure.
+name: c
+registers:
+  - { id: 0, class: gr32_abcd }
+  - { id: 1, class: gr32_abcd }
+  - { id: 2, class: gr32 }
+
+body: |
+  bb.0:
+    ; CHECK-LABEL: name: c
+    ; CHECK: [[MOV32ri:%[0-9]+]]:gr32_abcd = MOV32ri 512
+    ; CHECK-NEXT: INLINEASM &"", 1 /* sideeffect attdialect */, 2359305 /* reguse:GR32 */, [[MOV32ri]], 1 /* reguse */, implicit-def early-clobber $df
+    ; CHECK-NEXT: [[MOV32ri1:%[0-9]+]]:gr32_abcd = MOV32ri 512
+    ; CHECK-NEXT: INLINEASM &"", 1 /* sideeffect attdialect */, 2359305 /* reguse:GR32 */, [[MOV32ri1]], 1 /* reguse */, implicit-def early-clobber $df
+    ; CHECK-NEXT: RET 0
+    %2 = MOV32ri 512
+    %0 = COPY %2
+    INLINEASM &"", 1 /* sideeffect attdialect */, 2359305 /* reguse:GR32_ABCD */, %0:gr32_abcd, 1 /* clobber */, implicit-def early-clobber $df
+    %1 = COPY %2
+    INLINEASM &"", 1 /* sideeffect attdialect */, 2359305 /* reguse:GR32_ABCD */, %1:gr32_abcd, 1 /* clobber */, implicit-def early-clobber $df
+    RET 0
+...