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[Mips] Fix unable to handle inline assembly ends with compat-branch o… (
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#77291)

…n MIPS

Modify:
Add a global variable 'CurForbiddenSlotAttr' to save current
instruction's forbidden slot and whether set reorder. This is the
judgment condition for whether to add nop. We would add a couple of
'.set noreorder' and '.set reorder' to wrap the current instruction and
the next instruction.
Then we can get previous instruction`s forbidden slot attribute and
whether set reorder by 'CurForbiddenSlotAttr'.
If previous instruction has forbidden slot and .set reorder is active
and current instruction is CTI. Then emit a NOP after it.

Fix #61045.

Because https://reviews.llvm.org/D158589 was 'Needs Review' state, not
ending, so we commit pull request again.

(cherry picked from commit 96abee5)
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@yingopq @tstellar
yingopq authored and tstellar committed Feb 27, 2024
1 parent 6d8f929 commit e2182a6
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Showing 7 changed files with 202 additions and 35 deletions.
18 changes: 10 additions & 8 deletions lld/test/ELF/mips-pc-relocs.s
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Expand Up @@ -40,11 +40,13 @@ __start:
# ^-- (0x20020-0x20000)>>2
# CHECK-NEXT: 20004: beqc $5, $6, 0x20020
# ^-- (0x20020-4-0x20004)>>2
# CHECK-NEXT: 20008: beqzc $9, 0x20020
# ^-- (0x20020-4-0x20008)>>2
# CHECK-NEXT: 2000c: bc 0x20020
# ^-- (0x20020-4-0x2000c)>>2
# CHECK-NEXT: 20010: aluipc $2, 0
# ^-- %hi(0x20020-0x20010)
# CHECK-NEXT: 20014: addiu $2, $2, 12
# ^-- %lo(0x20020-0x20014)
# CHECK-NEXT: 20008: nop
# CHECK-NEXT: 2000c: beqzc $9, 0x20020
# ^-- (0x20020-4-0x2000c)>>2
# CHECK-NEXT: 20010: nop
# CHECK-NEXT: 20014: bc 0x20020
# ^-- (0x20020-4-0x200014)>>2
# CHECK-NEXT: 20018: aluipc $2, 0
# ^-- %hi(0x20020-0x20018)
# CHECK-NEXT: 2001c: addiu $2, $2, 4
# ^-- %lo(0x20020-0x2001c)
78 changes: 77 additions & 1 deletion llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,7 @@ class MipsAsmParser : public MCTargetAsmParser {
bool IsLittleEndian;
bool IsPicEnabled;
bool IsCpRestoreSet;
bool CurForbiddenSlotAttr;
int CpRestoreOffset;
unsigned GPReg;
unsigned CpSaveLocation;
Expand Down Expand Up @@ -552,6 +553,7 @@ class MipsAsmParser : public MCTargetAsmParser {

CurrentFn = nullptr;

CurForbiddenSlotAttr = false;
IsPicEnabled = getContext().getObjectFileInfo()->isPositionIndependent();

IsCpRestoreSet = false;
Expand Down Expand Up @@ -723,6 +725,16 @@ class MipsAsmParser : public MCTargetAsmParser {
return getSTI().hasFeature(Mips::FeatureGINV);
}

bool hasForbiddenSlot(const MCInstrDesc &MCID) const {
return !inMicroMipsMode() && (MCID.TSFlags & MipsII::HasForbiddenSlot);
}

bool SafeInForbiddenSlot(const MCInstrDesc &MCID) const {
return !(MCID.TSFlags & MipsII::IsCTI);
}

void onEndOfFile() override;

/// Warn if RegIndex is the same as the current AT.
void warnIfRegIndexIsAT(unsigned RegIndex, SMLoc Loc);

Expand Down Expand Up @@ -2307,7 +2319,41 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,

bool FillDelaySlot =
MCID.hasDelaySlot() && AssemblerOptions.back()->isReorder();
if (FillDelaySlot)

// Get previous instruction`s forbidden slot attribute and
// whether set reorder.
bool PrevForbiddenSlotAttr = CurForbiddenSlotAttr;

// Flag represents we set reorder after nop.
bool SetReorderAfterNop = false;

// If previous instruction has forbidden slot and .set reorder
// is active and current instruction is CTI.
// Then emit a NOP after it.
if (PrevForbiddenSlotAttr && !SafeInForbiddenSlot(MCID)) {
TOut.emitEmptyDelaySlot(false, IDLoc, STI);
// When 'FillDelaySlot' is true, the existing logic will add
// noreorder before instruction and reorder after it. So there
// need exclude this case avoiding two '.set reorder'.
// The format of the first case is:
// .set noreorder
// bnezc
// nop
// .set reorder
if (AssemblerOptions.back()->isReorder() && !FillDelaySlot) {
SetReorderAfterNop = true;
TOut.emitDirectiveSetReorder();
}
}

// Save current instruction`s forbidden slot and whether set reorder.
// This is the judgment condition for whether to add nop.
// We would add a couple of '.set noreorder' and '.set reorder' to
// wrap the current instruction and the next instruction.
CurForbiddenSlotAttr =
hasForbiddenSlot(MCID) && AssemblerOptions.back()->isReorder();

if (FillDelaySlot || CurForbiddenSlotAttr)
TOut.emitDirectiveSetNoReorder();

MacroExpanderResultTy ExpandResult =
Expand All @@ -2322,6 +2368,17 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
return true;
}

// When current instruction was not CTI, recover reorder state.
// The format of the second case is:
// .set noreoder
// bnezc
// add
// .set reorder
if (PrevForbiddenSlotAttr && !SetReorderAfterNop && !FillDelaySlot &&
AssemblerOptions.back()->isReorder()) {
TOut.emitDirectiveSetReorder();
}

// We know we emitted an instruction on the MER_NotAMacro or MER_Success path.
// If we're in microMIPS mode then we must also set EF_MIPS_MICROMIPS.
if (inMicroMipsMode()) {
Expand All @@ -2331,6 +2388,14 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,

// If this instruction has a delay slot and .set reorder is active,
// emit a NOP after it.
// The format of the third case is:
// .set noreorder
// bnezc
// nop
// .set noreorder
// j
// nop
// .set reorder
if (FillDelaySlot) {
TOut.emitEmptyDelaySlot(hasShortDelaySlot(Inst), IDLoc, STI);
TOut.emitDirectiveSetReorder();
Expand All @@ -2356,6 +2421,17 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
return false;
}

void MipsAsmParser::onEndOfFile() {
MipsTargetStreamer &TOut = getTargetStreamer();
SMLoc IDLoc = SMLoc();
// If has pending forbidden slot, fill nop and recover reorder.
if (CurForbiddenSlotAttr) {
TOut.emitEmptyDelaySlot(false, IDLoc, STI);
if (AssemblerOptions.back()->isReorder())
TOut.emitDirectiveSetReorder();
}
}

MipsAsmParser::MacroExpanderResultTy
MipsAsmParser::tryExpandInstruction(MCInst &Inst, SMLoc IDLoc, MCStreamer &Out,
const MCSubtargetInfo *STI) {
Expand Down
71 changes: 71 additions & 0 deletions llvm/test/CodeGen/Mips/llvm-ir/forbidden-slot-ir.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,71 @@
target triple = "mipsisa32r6el-unknown-linux-gnu"

; RUN: llc -filetype=asm %s -o - | FileCheck %s --check-prefix=MIPSELR6
; Function Attrs: noinline nounwind optnone uwtable
define i1 @foo0() nounwind {
; MIPSELR6: bnezc $1, $BB0_2
; MIPSELR6-NEXT: nop
; MIPSELR6: jr $ra
entry:
%0 = icmp eq i32 0, 1
br i1 %0, label %2, label %3
ret i1 %0
2:
ret i1 %0
3:
ret i1 %0
}

define i32 @foo1() nounwind {
; MIPSELR6: addiu $2, $2, 1
; MIPSELR6-NEXT: .set noreorder
; MIPSELR6-NEXT: beqzc $2, $tmp0
; MIPSELR6-NEXT: nop
; MIPSELR6-NEXT: .set reorder
; MIPSELR6: jrc $ra
entry:
%0 = tail call i32 asm "1: addiu $0, $0, 1; beqzc $0, 1b", "=r"() nounwind
ret i32 %0
}

define i32 @foo2() nounwind {
; MIPSELR6: .set push
; MIPSELR6-NEXT: .set at
; MIPSELR6-NEXT: .set macro
; MIPSELR6-NEXT: .set reorder
; MIPSELR6: .set noreorder
; MIPSELR6-NEXT: beqzc $9, End
; MIPSELR6-NEXT: nop
; MIPSELR6-NEXT: .set reorder
; MIPSELR6: addiu $9, $9, 1
entry:
%0 = tail call i32 asm "beqzc $$t1, End", "=r"() nounwind
%1 = tail call i32 asm "addiu $$t1, $$t1, 1", "=r"() nounwind
%2 = add nsw i32 %1, %0
ret i32 %2
}

define i32 @foo3() nounwind {
; MIPSELR6: addiu $2, $2, 1
; MIPSELR6-NEXT: .set noreorder
; MIPSELR6-NEXT: beqzc $2, $tmp1
; MIPSELR6-NEXT: nop
; MIPSELR6-NEXT: .set noreorder
; MIPSELR6-NEXT: j End
; MIPSELR6-NEXT: nop
; MIPSELR6-NEXT: .set reorder
entry:
%0 = tail call i32 asm "1: addiu $0, $0, 1; beqzc $0, 1b; j End", "=r"() nounwind
ret i32 %0
}

define i32 @foo4() nounwind {
; MIPSELR6: addiu $2, $2, 1
; MIPSELR6-NEXT: .set noreorder
; MIPSELR6-NEXT: beqzc $2, $tmp2
; MIPSELR6-NEXT: addiu $2, $2, 1
; MIPSELR6-NEXT: .set reorder
entry:
%0 = tail call i32 asm "1: addiu $0, $0, 1; beqzc $0, 1b; addiu $0, $0, 1", "=r"() nounwind
ret i32 %0
}
18 changes: 18 additions & 0 deletions llvm/test/MC/Mips/forbidden-slot.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
# RUN: llvm-mc -assemble -mcpu=mips64r6 -arch=mips64el -filetype=obj %s -o tmp.o
# RUN: llvm-objdump -d tmp.o | FileCheck %s --check-prefix=MIPSELR6

# MIPSELR6: 0000000000000000 <aaa>:
# MIPSELR6-NEXT: beqzc $13, 0x0 <aaa>
# MIPSELR6-NEXT: b 0x0 <aaa>
# MIPSELR6: 0000000000000008 <bbb>:
# MIPSELR6-NEXT: beqzc $13, 0x8 <bbb>
# MIPSELR6-NEXT: nop <aaa>
# MIPSELR6: b 0x8 <bbb>
.set noreorder
aaa:
beqzc $t1, aaa
b aaa
.set reorder
bbb:
beqzc $t1, bbb
b bbb
22 changes: 11 additions & 11 deletions llvm/test/MC/Mips/mips32r6/relocations.s
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Original file line number Diff line number Diff line change
Expand Up @@ -52,17 +52,17 @@
# CHECK-ELF: Relocations [
# CHECK-ELF: 0x0 R_MIPS_PC19_S2 bar
# CHECK-ELF: 0x4 R_MIPS_PC16 bar
# CHECK-ELF: 0x8 R_MIPS_PC16 bar
# CHECK-ELF: 0xC R_MIPS_PC21_S2 bar
# CHECK-ELF: 0x10 R_MIPS_PC21_S2 bar
# CHECK-ELF: 0x14 R_MIPS_PC26_S2 bar
# CHECK-ELF: 0x18 R_MIPS_PC26_S2 bar
# CHECK-ELF: 0x1C R_MIPS_PCHI16 bar
# CHECK-ELF: 0x20 R_MIPS_PCLO16 bar
# CHECK-ELF: 0x24 R_MIPS_PC19_S2 bar
# CHECK-ELF: 0x28 R_MIPS_PC19_S2 bar
# CHECK-ELF: 0x2C R_MIPS_LO16 bar
# CHECK-ELF: 0x30 R_MIPS_LO16 bar
# CHECK-ELF: 0xC R_MIPS_PC16 bar
# CHECK-ELF: 0x14 R_MIPS_PC21_S2 bar
# CHECK-ELF: 0x1C R_MIPS_PC21_S2 bar
# CHECK-ELF: 0x24 R_MIPS_PC26_S2 bar
# CHECK-ELF: 0x28 R_MIPS_PC26_S2 bar
# CHECK-ELF: 0x2C R_MIPS_PCHI16 bar
# CHECK-ELF: 0x30 R_MIPS_PCLO16 bar
# CHECK-ELF: 0x34 R_MIPS_PC19_S2 bar
# CHECK-ELF: 0x38 R_MIPS_PC19_S2 bar
# CHECK-ELF: 0x3C R_MIPS_LO16 bar
# CHECK-ELF: 0x40 R_MIPS_LO16 bar
# CHECK-ELF: ]

addiupc $2,bar
Expand Down
26 changes: 13 additions & 13 deletions llvm/test/MC/Mips/mips64r6/relocations.s
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Original file line number Diff line number Diff line change
Expand Up @@ -59,19 +59,19 @@
# CHECK-ELF: Relocations [
# CHECK-ELF: 0x0 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x4 R_MIPS_PC16/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x8 R_MIPS_PC16/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0xC R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x10 R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x14 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x18 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x1C R_MIPS_PCHI16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x20 R_MIPS_PCLO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x24 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x28 R_MIPS_PC18_S3/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x2C R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x30 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x34 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x38 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0xC R_MIPS_PC16/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x14 R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x1C R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x24 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x28 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
# CHECK-ELF: 0x2C R_MIPS_PCHI16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x30 R_MIPS_PCLO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x34 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x38 R_MIPS_PC18_S3/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x3C R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x40 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x44 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: 0x48 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
# CHECK-ELF: ]

addiupc $2,bar
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/MC/Mips/relocation.s
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Original file line number Diff line number Diff line change
Expand Up @@ -237,7 +237,7 @@ baz: .long foo // RELOC: R_MIPS_32 foo
// ENCLE: addiu $2, $3, %tprel_lo(foo) # encoding: [A,A,0x62,0x24]
// FIXUP: # fixup A - offset: 0, value: %tprel_lo(foo), kind: fixup_Mips_TPREL_LO

// DATA-NEXT: 00C0: D85FFFFF CBFFFFFF EC580000 EC480000
// DATA-NEXT: 00C0: D85FFFFF 00000000 CBFFFFFF EC580000
// ?????: R_MIPS_GLOB_DAT foo
.set mips32r6
beqzc $2, foo // RELOC: R_MIPS_PC21_S2 foo
Expand All @@ -262,7 +262,7 @@ baz: .long foo // RELOC: R_MIPS_32 foo
// ENCLE: lwpc $2, foo # encoding: [A,A,0b01001AAA,0xec]
// FIXUP: # fixup A - offset: 0, value: foo, kind: fixup_MIPS_PC19_S2

// DATA-NEXT: 00D0: 24620000 24620000 00000000
// DATA-NEXT: 00D0: EC480000 24620000 24620000 00000000
addiu $2, $3, %pcrel_hi(foo) // RELOC: R_MIPS_PCHI16 foo
// ENCBE: addiu $2, $3, %pcrel_hi(foo) # encoding: [0x24,0x62,A,A]
// ENCLE: addiu $2, $3, %pcrel_hi(foo) # encoding: [A,A,0x62,0x24]
Expand Down

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