[llvm-branch-commits] [llvm] d73eb82 - [llvm][IfConversion] update successor list when merging INLINEASM_BR
Tobias Hieta via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Thu Feb 9 05:00:59 PST 2023
Author: Nick Desaulniers
Date: 2023-02-09T13:55:14+01:00
New Revision: d73eb820244b7b02e95ee3e47238f6f6527180c5
URL: https://github.com/llvm/llvm-project/commit/d73eb820244b7b02e95ee3e47238f6f6527180c5
DIFF: https://github.com/llvm/llvm-project/commit/d73eb820244b7b02e95ee3e47238f6f6527180c5.diff
LOG: [llvm][IfConversion] update successor list when merging INLINEASM_BR
If this successor list is not correct, then branch-folding may
incorrectly think that the indirect target is dead and remove it. This
results in a dangling reference to the removed block as an operand to
the INLINEASM_BR, which later will get AsmPrinted into code that doesn't
assemble.
This was made more obvious by, but is not a regression of
https://reviews.llvm.org/D130316.
Fixes: https://github.com/llvm/llvm-project/issues/60346
Reviewed By: efriedma, void
Differential Revision: https://reviews.llvm.org/D142924
(cherry picked from commit 07c7784d7bf69b9944b92ecc283cac823bcfce16)
Added:
Modified:
llvm/lib/CodeGen/IfConversion.cpp
llvm/test/CodeGen/ARM/inlineasmbr-if-cvt.mir
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/IfConversion.cpp b/llvm/lib/CodeGen/IfConversion.cpp
index 105ab908d3fab..936de316e5754 100644
--- a/llvm/lib/CodeGen/IfConversion.cpp
+++ b/llvm/lib/CodeGen/IfConversion.cpp
@@ -2244,6 +2244,15 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) {
assert(!FromMBB.hasAddressTaken() &&
"Removing a BB whose address is taken!");
+ // If we're about to splice an INLINEASM_BR from FromBBI, we need to update
+ // ToBBI's successor list accordingly.
+ if (FromMBB.mayHaveInlineAsmBr())
+ for (MachineInstr &MI : FromMBB)
+ if (MI.getOpcode() == TargetOpcode::INLINEASM_BR)
+ for (MachineOperand &MO : MI.operands())
+ if (MO.isMBB() && !ToBBI.BB->isSuccessor(MO.getMBB()))
+ ToBBI.BB->addSuccessor(MO.getMBB(), BranchProbability::getZero());
+
// In case FromMBB contains terminators (e.g. return instruction),
// first move the non-terminator instructions, then the terminators.
MachineBasicBlock::iterator FromTI = FromMBB.getFirstTerminator();
diff --git a/llvm/test/CodeGen/ARM/inlineasmbr-if-cvt.mir b/llvm/test/CodeGen/ARM/inlineasmbr-if-cvt.mir
index 7b41aa41b823e..ad45edc9835f5 100644
--- a/llvm/test/CodeGen/ARM/inlineasmbr-if-cvt.mir
+++ b/llvm/test/CodeGen/ARM/inlineasmbr-if-cvt.mir
@@ -1,6 +1,6 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
# RUN: llc -start-before=if-converter -stop-after=if-converter -o - %s \
-# RUN: | FileCheck %s
+# RUN: -verify-machineinstrs | FileCheck %s
--- |
; ModuleID = 'reduced.ll'
source_filename = "reduced.ll"
@@ -80,14 +80,23 @@ machineFunctionInfo: {}
body: |
; CHECK-LABEL: name: tusb1210_chg_det_work
; CHECK: bb.0.entry:
- ; CHECK-NEXT: successors:
+ ; CHECK-NEXT: successors: %bb.1(0x80000000), %bb.2(0x80000000)
; CHECK-NEXT: liveins: $r0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: TSTri killed renamable $r0, 1, 14 /* CC::al */, $noreg, implicit-def $cpsr
; CHECK-NEXT: renamable $r0 = MOVi 0, 1 /* CC::ne */, $cpsr, $noreg
- ; CHECK-NEXT: dead renamable $r0 = MOVi 1, 0 /* CC::eq */, killed $cpsr, $noreg, implicit killed $r0
- ; FIXME: %bb.-1 is a dangling reference!!!
- ; CHECK-NEXT: INLINEASM_BR &".word b, ${1:l}, ${0:c}\0A\09", 9 /* sideeffect mayload attdialect */, 13 /* imm */, 0, 13 /* imm */, %bb.-1
+ ; CHECK-NEXT: renamable $r0 = MOVi 1, 0 /* CC::eq */, killed $cpsr, $noreg, implicit killed $r0
+ ; CHECK-NEXT: INLINEASM_BR &".word b, ${1:l}, ${0:c}\0A\09", 9 /* sideeffect mayload attdialect */, 13 /* imm */, 0, 13 /* imm */, %bb.1
+ ; CHECK-NEXT: B %bb.2
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: bb.1.if.end.sink.split (machine-block-address-taken, inlineasm-br-indirect-target):
+ ; CHECK-NEXT: successors: %bb.2(0x80000000)
+ ; CHECK-NEXT: liveins: $r0
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: renamable $r1 = MOVi 0, 14 /* CC::al */, $noreg, $noreg
+ ; CHECK-NEXT: STRi12 killed renamable $r0, killed renamable $r1, 0, 14 /* CC::al */, $noreg :: (store (s32) into `ptr null`)
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: bb.2.if.end:
; CHECK-NEXT: BX_RET 14 /* CC::al */, $noreg
bb.0.entry:
successors: %bb.4(0x40000000), %bb.1(0x40000000)
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