[llvm] [Statepoint] Treat undef operands less specially (PR #119682)
Matt Arsenault via llvm-commits
llvm-commits at lists.llvm.org
Sun Dec 15 17:58:55 PST 2024
https://github.com/arsenm updated https://github.com/llvm/llvm-project/pull/119682
>From 28de01787331dc5f4c1e39c239efdd07ffc5d324 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Mon, 28 Mar 2022 14:11:28 -0400
Subject: [PATCH] [Statepoint] Treat undef operands less specially
This reverts commit f7443905af1e06eaacda1e437fff8d54dc89c487.
This is to avoid an assertion if an undef operand appears in a
stackmap. This is important to avoid hitting verifier errors
when register allocation starts adding undefs in error scenarios.
Rather than trying to treat undef operands as special, leave them
alone and avoid producing an invalid spill. It would a bit more
precise to produce a spill of an undef register here, but that's not
exposed through the storeRegToStackSlot API.
https://reviews.llvm.org/D122605
This was an alternative to https://reviews.llvm.org/D122582
---
.../CodeGen/FixupStatepointCallerSaved.cpp | 2 -
llvm/lib/CodeGen/StackMaps.cpp | 6 --
.../X86/stackmap-undef-operand-anyregcc.mir | 77 +++++++++++++++++++
.../CodeGen/X86/statepoint-fixup-undef.mir | 8 +-
4 files changed, 81 insertions(+), 12 deletions(-)
create mode 100644 llvm/test/CodeGen/X86/stackmap-undef-operand-anyregcc.mir
diff --git a/llvm/lib/CodeGen/FixupStatepointCallerSaved.cpp b/llvm/lib/CodeGen/FixupStatepointCallerSaved.cpp
index 3bb9da5f1a37bb..0ebe845e473fd6 100644
--- a/llvm/lib/CodeGen/FixupStatepointCallerSaved.cpp
+++ b/llvm/lib/CodeGen/FixupStatepointCallerSaved.cpp
@@ -381,8 +381,6 @@ class StatepointState {
EndIdx = MI.getNumOperands();
Idx < EndIdx; ++Idx) {
MachineOperand &MO = MI.getOperand(Idx);
- // Leave `undef` operands as is, StackMaps will rewrite them
- // into a constant.
if (!MO.isReg() || MO.isImplicit() || MO.isUndef())
continue;
Register Reg = MO.getReg();
diff --git a/llvm/lib/CodeGen/StackMaps.cpp b/llvm/lib/CodeGen/StackMaps.cpp
index 81b288df3b07e0..7480963c1f5217 100644
--- a/llvm/lib/CodeGen/StackMaps.cpp
+++ b/llvm/lib/CodeGen/StackMaps.cpp
@@ -268,12 +268,6 @@ StackMaps::parseOperand(MachineInstr::const_mop_iterator MOI,
if (MOI->isImplicit())
return ++MOI;
- if (MOI->isUndef()) {
- // Record `undef` register as constant. Use same value as ISel uses.
- Locs.emplace_back(Location::Constant, sizeof(int64_t), 0, 0xFEFEFEFE);
- return ++MOI;
- }
-
assert(MOI->getReg().isPhysical() &&
"Virtreg operands should have been rewritten before now.");
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(MOI->getReg());
diff --git a/llvm/test/CodeGen/X86/stackmap-undef-operand-anyregcc.mir b/llvm/test/CodeGen/X86/stackmap-undef-operand-anyregcc.mir
new file mode 100644
index 00000000000000..3c6390ba2379c8
--- /dev/null
+++ b/llvm/test/CodeGen/X86/stackmap-undef-operand-anyregcc.mir
@@ -0,0 +1,77 @@
+# RUN: llc -mtriple=x86_64-apple-darwin -start-after=virtregrewriter -o - %s | FileCheck %s
+
+# Check there's no assertion for anyregcc with an undef operand to a stackmap.
+
+# CHECK: __LLVM_StackMaps:
+# CHECK-NEXT: .byte 3
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .long 1
+# CHECK-NEXT: .long 0
+# CHECK-NEXT: .long 1
+# CHECK-NEXT: .quad _undef_anyregcc_patchpoint
+# CHECK-NEXT: .quad 8
+# CHECK-NEXT: .quad 1
+# CHECK-NEXT: .quad 12
+# CHECK-NEXT: .long Ltmp0-_undef_anyregcc_patchpoint
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .short 2
+# CHECK-NEXT: .byte 1
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .short 8
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .long 0
+# CHECK-NEXT: .byte 1
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .short 8
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .long 0
+# CHECK-NEXT: .p2align 3, 0x0
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .short 7
+# CHECK-NEXT: .short 0
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .byte 8
+# CHECK-NEXT: .short 3
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .byte 8
+# CHECK-NEXT: .short 7
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .byte 8
+# CHECK-NEXT: .short 12
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .byte 8
+# CHECK-NEXT: .short 13
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .byte 8
+# CHECK-NEXT: .short 14
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .byte 8
+# CHECK-NEXT: .short 15
+# CHECK-NEXT: .byte 0
+# CHECK-NEXT: .byte 8
+# CHECK-NEXT: .p2align 3
+---
+name: undef_anyregcc_patchpoint
+tracksRegLiveness: true
+frameInfo:
+ hasPatchPoint: true
+ hasCalls: true
+ adjustsStack: true
+fixedStack:
+ - { id: 0, type: default, offset: 72, size: 8, alignment: 8, stack-id: default,
+ isImmutable: true, isAliased: false, callee-saved-register: '', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body: |
+ bb.0:
+ liveins: $rcx, $rdi, $rdx, $rsi, $r8, $r9
+
+ ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+ dead renamable $rax = MOV64rm %fixed-stack.0, 1, $noreg, 0, $noreg :: (load (s64) from %fixed-stack.0)
+ renamable $rax = PATCHPOINT 12, 15, 0, 1, 13, undef renamable $rax, csr_64_allregs, implicit-def dead early-clobber $r11, implicit-def $rsp, implicit-def $ssp
+ ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+ RET 0, $rax
+
+...
diff --git a/llvm/test/CodeGen/X86/statepoint-fixup-undef.mir b/llvm/test/CodeGen/X86/statepoint-fixup-undef.mir
index 4a18351bde493d..edb0d517d5d52f 100644
--- a/llvm/test/CodeGen/X86/statepoint-fixup-undef.mir
+++ b/llvm/test/CodeGen/X86/statepoint-fixup-undef.mir
@@ -181,13 +181,13 @@ body: |
; STACKMAP-NEXT: .short 3
; STACKMAP-NEXT: .short 0
; STACKMAP-NEXT: .long 0
- ; This is a constant 0xFEFEFEFE we are looking for
- ; STACKMAP-NEXT: .byte 4
+ ; This is entry we're looking for
+ ; STACKMAP-NEXT: .byte 1
; STACKMAP-NEXT: .byte 0
- ; STACKMAP-NEXT: .short 8
+ ; STACKMAP-NEXT: .short 4
; STACKMAP-NEXT: .short 0
; STACKMAP-NEXT: .short 0
- ; STACKMAP-NEXT: .long -16843010
+ ; STACKMAP-NEXT: .long 0
; STACKMAP-NEXT: .byte 4
; STACKMAP-NEXT: .byte 0
; STACKMAP-NEXT: .short 8
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