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[X86] Fix X86FixupLEAs displacement check for other types of operands #200705

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Merged
duk-37 merged 3 commits into from
Jun 1, 2026
Merged

[X86] Fix X86FixupLEAs displacement check for other types of operands #200705

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d4b3743
fix LEA displacement calculation
duk-37 Jun 1, 2026
77431cc
test
duk-37 Jun 1, 2026
a14b709
Merge branch 'main' into bugfix/lea-disp-fix
duk-37 Jun 1, 2026
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12 changes: 6 additions & 6 deletions llvm/lib/Target/X86/X86FixupLEAs.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -343,9 +343,9 @@ static inline bool hasInefficientLEABaseReg(const MachineOperand &Base,
Index.getReg().isValid();
}

static inline bool hasLEAOffset(const MachineOperand &Offset) {
return (Offset.isImm() && Offset.getImm() != 0) || Offset.isGlobal() ||
Offset.isBlockAddress();
// Returns true if this operand may have a non-zero offset.
static inline bool mayHaveOffset(const MachineOperand &Offset) {
return !(Offset.isImm() && Offset.getImm() == 0);
}

static inline unsigned getADDrrFromLEA(unsigned LEAOpcode) {
Expand Down Expand Up @@ -790,7 +790,7 @@ void FixupLEAsImpl::processInstrForSlow3OpLEA(MachineBasicBlock::iterator &I,
// Only do this if the LEA would otherwise be split into 2-instruction
// (either it has a an Offset or neither base nor index are dst)
if (IsScale1 && BaseReg == IndexReg &&
(hasLEAOffset(Offset) || (IsInefficientBase && !BaseOrIndexIsDst))) {
(mayHaveOffset(Offset) || (IsInefficientBase && !BaseOrIndexIsDst))) {
NewMI = BuildMI(MBB, MI, MI.getDebugLoc(), TII->get(LEAOpcode))
.add(Dest)
.addReg(0)
Expand Down Expand Up @@ -845,7 +845,7 @@ void FixupLEAsImpl::processInstrForSlow3OpLEA(MachineBasicBlock::iterator &I,
// replace the instruction.
if (NewMI) {
// Create ADD instruction for the Offset in case of 3-Ops LEA.
if (hasLEAOffset(Offset)) {
if (mayHaveOffset(Offset)) {
if (OptIncDec && Offset.isImm() &&
(Offset.getImm() == 1 || Offset.getImm() == -1)) {
unsigned NewOpc =
Expand Down Expand Up @@ -877,7 +877,7 @@ void FixupLEAsImpl::processInstrForSlow3OpLEA(MachineBasicBlock::iterator &I,
return;

// lea (%base,%index,1), %dst => mov %base,%dst; add %index,%dst
if (IsScale1 && !hasLEAOffset(Offset)) {
if (IsScale1 && !mayHaveOffset(Offset)) {
bool BIK = Base.isKill() && BaseReg != IndexReg;
TII->copyPhysReg(MBB, MI, MI.getDebugLoc(), DestReg, BaseReg, BIK);
LLVM_DEBUG(MI.getPrevNode()->dump(););
Expand Down
20 changes: 20 additions & 0 deletions llvm/test/CodeGen/X86/lea-fixup-mcsymbol.mir
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@@ -0,0 +1,20 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 3
# RUN: llc -mtriple=x86_64-unknown-linux-gnu -mattr=slow-3ops-lea -run-pass x86-fixup-leas -o - %s | FileCheck %s
# RUN: llc -mtriple=x86_64-unknown-linux-gnu -mattr=slow-3ops-lea -passes="require<profile-summary>,function(machine-function(x86-fixup-leas))" -o - %s | FileCheck %s

--- |
define void @test() nounwind {
ret void
}

---
name: test
body: |
bb.0:
; CHECK-LABEL: name: test
; CHECK: renamable $rax = LEA64r renamable $rbx, 1, renamable $rbp, 0, $noreg
; CHECK-NEXT: $rax = ADD64ri32 $rax, target-flags(x86-gotoff) <mcsymbol foo>, implicit-def $eflags
; CHECK-NEXT: JMP64r renamable $rax
renamable $rax = LEA64r renamable $rbp, 1, renamable $rbx, target-flags(x86-gotoff) <mcsymbol foo>, $noreg
JMP64r renamable $rax
...