[llvm] 4d3c427 - [CodeGen] Use first EHLabel as a stop gate for live range shrinking (#114195)
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Fri Nov 1 19:13:22 PDT 2024
Author: Mirko
Date: 2024-11-01T19:13:18-07:00
New Revision: 4d3c427f339562b73938296d77103baf9ab9dc4b
URL: https://github.com/llvm/llvm-project/commit/4d3c427f339562b73938296d77103baf9ab9dc4b
DIFF: https://github.com/llvm/llvm-project/commit/4d3c427f339562b73938296d77103baf9ab9dc4b.diff
LOG: [CodeGen] Use first EHLabel as a stop gate for live range shrinking (#114195)
This fixes issue #114194
The issue happens during the `LiveRangeShrink` pass, which runs early,
before phi elimination. LandingPads, which are lowered to EHLabels, need
to be the first non phi instruction in an EHPad. In case of a phi node
being in front of the EHLabel and a use being after the EHLabel, we
hoist the use in front of the label.
This results in a portion of the landingpad missing due to being hoisted
in front of the label.
Added:
llvm/test/CodeGen/X86/lrshrink-ehpad-phis.ll
Modified:
llvm/lib/CodeGen/LiveRangeShrink.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/LiveRangeShrink.cpp b/llvm/lib/CodeGen/LiveRangeShrink.cpp
index 3e3e3e51bfe9c6..f4bf47c3ae158f 100644
--- a/llvm/lib/CodeGen/LiveRangeShrink.cpp
+++ b/llvm/lib/CodeGen/LiveRangeShrink.cpp
@@ -124,15 +124,24 @@ bool LiveRangeShrink::runOnMachineFunction(MachineFunction &MF) {
for (MachineBasicBlock &MBB : MF) {
if (MBB.empty())
continue;
- bool SawStore = false;
- BuildInstOrderMap(MBB.begin(), IOM);
+
+ MachineBasicBlock::iterator Next = MBB.begin();
+ if (MBB.isEHPad()) {
+ // Do not track PHIs in IOM when handling EHPads.
+ // Otherwise their uses may be hoisted outside a landingpad range.
+ Next = MBB.SkipPHIsLabelsAndDebug(Next);
+ if (Next == MBB.end())
+ continue;
+ }
+
+ BuildInstOrderMap(Next, IOM);
+ Next = MBB.SkipPHIsLabelsAndDebug(Next);
UseMap.clear();
+ bool SawStore = false;
- for (MachineBasicBlock::iterator Next = MBB.begin(); Next != MBB.end();) {
+ while (Next != MBB.end()) {
MachineInstr &MI = *Next;
- ++Next;
- if (MI.isPHI() || MI.isDebugOrPseudoInstr())
- continue;
+ Next = MBB.SkipPHIsLabelsAndDebug(++Next);
if (MI.mayStore())
SawStore = true;
diff --git a/llvm/test/CodeGen/X86/lrshrink-ehpad-phis.ll b/llvm/test/CodeGen/X86/lrshrink-ehpad-phis.ll
new file mode 100755
index 00000000000000..b9afb996973548
--- /dev/null
+++ b/llvm/test/CodeGen/X86/lrshrink-ehpad-phis.ll
@@ -0,0 +1,112 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc -mtriple x86_64-unknown-linux-gnu %s -o - | FileCheck %s
+
+declare i32 @__gxx_personality_v0(...)
+declare void @maythrow()
+declare void @cleanup(i32)
+
+ at external_bool = external global i1
+ at externalA = external global i32
+ at externalB = external global i32
+ at externalC = external global i32
+ at externalD = external global i32
+
+define void @test() personality ptr @__gxx_personality_v0 {
+; CHECK-LABEL: test:
+; CHECK: # %bb.0:
+; CHECK-NEXT: pushq %rbp
+; CHECK-NEXT: .cfi_def_cfa_offset 16
+; CHECK-NEXT: pushq %r15
+; CHECK-NEXT: .cfi_def_cfa_offset 24
+; CHECK-NEXT: pushq %r14
+; CHECK-NEXT: .cfi_def_cfa_offset 32
+; CHECK-NEXT: pushq %r13
+; CHECK-NEXT: .cfi_def_cfa_offset 40
+; CHECK-NEXT: pushq %r12
+; CHECK-NEXT: .cfi_def_cfa_offset 48
+; CHECK-NEXT: pushq %rbx
+; CHECK-NEXT: .cfi_def_cfa_offset 56
+; CHECK-NEXT: pushq %rax
+; CHECK-NEXT: .cfi_def_cfa_offset 64
+; CHECK-NEXT: .cfi_offset %rbx, -56
+; CHECK-NEXT: .cfi_offset %r12, -48
+; CHECK-NEXT: .cfi_offset %r13, -40
+; CHECK-NEXT: .cfi_offset %r14, -32
+; CHECK-NEXT: .cfi_offset %r15, -24
+; CHECK-NEXT: .cfi_offset %rbp, -16
+; CHECK-NEXT: movq external_bool at GOTPCREL(%rip), %rax
+; CHECK-NEXT: cmpb $1, (%rax)
+; CHECK-NEXT: jne .LBB0_3
+; CHECK-NEXT: # %bb.1: # %branchA
+; CHECK-NEXT: movq externalA at GOTPCREL(%rip), %rax
+; CHECK-NEXT: movl (%rax), %eax
+; CHECK-NEXT: movl %eax, {{[-0-9]+}}(%r{{[sb]}}p) # 4-byte Spill
+; CHECK-NEXT: movq externalC at GOTPCREL(%rip), %rax
+; CHECK-NEXT: movl (%rax), %eax
+; CHECK-NEXT: movl %eax, (%rsp) # 4-byte Spill
+; CHECK-NEXT: #APP
+; CHECK-NEXT: #NO_APP
+; CHECK-NEXT: .Ltmp2:
+; CHECK-NEXT: callq maythrow at PLT
+; CHECK-NEXT: .Ltmp3:
+; CHECK-NEXT: jmp .LBB0_4
+; CHECK-NEXT: .LBB0_3: # %branchB
+; CHECK-NEXT: movq externalB at GOTPCREL(%rip), %rax
+; CHECK-NEXT: movl (%rax), %eax
+; CHECK-NEXT: movl %eax, {{[-0-9]+}}(%r{{[sb]}}p) # 4-byte Spill
+; CHECK-NEXT: movq externalD at GOTPCREL(%rip), %rax
+; CHECK-NEXT: movl (%rax), %eax
+; CHECK-NEXT: movl %eax, (%rsp) # 4-byte Spill
+; CHECK-NEXT: #APP
+; CHECK-NEXT: #NO_APP
+; CHECK-NEXT: .Ltmp0:
+; CHECK-NEXT: callq maythrow at PLT
+; CHECK-NEXT: .Ltmp1:
+; CHECK-NEXT: .LBB0_4: # %end
+; CHECK-NEXT: addq $8, %rsp
+; CHECK-NEXT: .cfi_def_cfa_offset 56
+; CHECK-NEXT: popq %rbx
+; CHECK-NEXT: .cfi_def_cfa_offset 48
+; CHECK-NEXT: popq %r12
+; CHECK-NEXT: .cfi_def_cfa_offset 40
+; CHECK-NEXT: popq %r13
+; CHECK-NEXT: .cfi_def_cfa_offset 32
+; CHECK-NEXT: popq %r14
+; CHECK-NEXT: .cfi_def_cfa_offset 24
+; CHECK-NEXT: popq %r15
+; CHECK-NEXT: .cfi_def_cfa_offset 16
+; CHECK-NEXT: popq %rbp
+; CHECK-NEXT: .cfi_def_cfa_offset 8
+; CHECK-NEXT: retq
+; CHECK-NEXT: .LBB0_2: # %lpad
+; CHECK-NEXT: .cfi_def_cfa_offset 64
+; CHECK-NEXT: .Ltmp4:
+; CHECK-NEXT: movq %rax, %rbx
+; CHECK-NEXT: movl {{[-0-9]+}}(%r{{[sb]}}p), %edi # 4-byte Reload
+; CHECK-NEXT: addl (%rsp), %edi # 4-byte Folded Reload
+; CHECK-NEXT: callq cleanup at PLT
+; CHECK-NEXT: movq %rbx, %rdi
+; CHECK-NEXT: callq _Unwind_Resume at PLT
+ %1 = load i1, ptr @external_bool
+ br i1 %1, label %branchA, label %branchB
+branchA:
+ %valueA = load i32, ptr @externalA
+ %valueC = load i32, ptr @externalC
+ call void asm sideeffect "", "~{rbp},~{rsi},~{rdi},~{rcx},~{rbx},~{r12},~{r13},~{r14},~{r15},~{flags}"()
+ invoke void @maythrow() to label %end unwind label %lpad
+branchB:
+ %valueB = load i32, ptr @externalB
+ %valueD = load i32, ptr @externalD
+ call void asm sideeffect "", "~{rbp},~{rsi},~{rdi},~{rcx},~{rbx},~{r12},~{r13},~{r14},~{r15},~{flags}"()
+ invoke void @maythrow() to label %end unwind label %lpad
+lpad:
+ %phiValue = phi i32 [%valueA, %branchA], [%valueB, %branchB]
+ %phiValue2 = phi i32 [%valueC, %branchA], [%valueD, %branchB]
+ %lp = landingpad { ptr, i32 }
+ cleanup
+ %3 = add i32 %phiValue2, %phiValue
+ call void @cleanup(i32 %3)
+ resume { ptr, i32 } %lp
+end:
+ ret void
+}
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