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[LoongArch] Allow recognition of b{lt,gt,le,ge}z in disassembly #132620

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Merged
merged 1 commit into from
Mar 26, 2025
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[LoongArch] Allow recognition of b{lt,gt,le,ge}z in disassembly #132620

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22 changes: 13 additions & 9 deletions llvm/lib/Target/LoongArch/LoongArchInstrInfo.td
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Original file line number Diff line number Diff line change
Expand Up @@ -2294,11 +2294,15 @@ def : InstAlias<"move $dst, $src", (OR GPR:$dst, GPR:$src, R0)>;
def : InstAlias<"ret", (JIRL R0, R1, 0)>;
def : InstAlias<"jr $rj", (JIRL R0, GPR:$rj, 0)>;

// Branches implemented with alias.
// Always output the canonical mnemonic for the pseudo branch instructions.
// The GNU tools emit the canonical mnemonic for the branch pseudo instructions
// as well (e.g. "bgt" will be recognised by the assembler but never printed by
// objdump). Match this behaviour by setting a zero weight.
// Branches implemented with aliases.
// Disassemble branch instructions not having a $zero operand to the
// canonical mnemonics respectively, but disassemble BLT/BGE with a $zero
// operand to the corresponding pseudo-instruction.
// GNU Binutils behave like this since 2.41, e.g. "bgt" will be recognised
// by the assembler but always disassembles as "blt" by objdump, while "bgtz"
// will come back intact.
// Match this behaviour by setting a zero weight for the b{gt,le}{,u}
// patterns only.
def : InstAlias<"bgt $rj, $rd, $imm16",
(BLT GPR:$rd, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
def : InstAlias<"bgtu $rj, $rd, $imm16",
Expand All @@ -2308,13 +2312,13 @@ def : InstAlias<"ble $rj, $rd, $imm16",
def : InstAlias<"bleu $rj, $rd, $imm16",
(BGEU GPR:$rd, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
def : InstAlias<"bltz $rd, $imm16",
(BLT GPR:$rd, R0, simm16_lsl2_br:$imm16), 0>;
(BLT GPR:$rd, R0, simm16_lsl2_br:$imm16)>;
def : InstAlias<"bgtz $rj, $imm16",
(BLT R0, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
(BLT R0, GPR:$rj, simm16_lsl2_br:$imm16)>;
def : InstAlias<"blez $rj, $imm16",
(BGE R0, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
(BGE R0, GPR:$rj, simm16_lsl2_br:$imm16)>;
def : InstAlias<"bgez $rd, $imm16",
(BGE GPR:$rd, R0, simm16_lsl2_br:$imm16), 0>;
(BGE GPR:$rd, R0, simm16_lsl2_br:$imm16)>;

// Load immediate.
let hasSideEffects = 0, mayLoad = 0, mayStore = 0, isCodeGenOnly = 0,
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8 changes: 4 additions & 4 deletions llvm/test/MC/LoongArch/Macros/aliases-br.s
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Expand Up @@ -9,10 +9,10 @@ ble $a1, $a0, 16
bleu $a1, $a0, 16
# CHECK-NEXT: bgeu $a0, $a1, 16
bltz $a0, 16
# CHECK-NEXT: blt $a0, $zero, 16
# CHECK-NEXT: bltz $a0, 16
bgtz $a0, 16
# CHECK-NEXT: blt $zero, $a0, 16
# CHECK-NEXT: bgtz $a0, 16
blez $a0, 16
# CHECK-NEXT: bge $zero, $a0, 16
# CHECK-NEXT: blez $a0, 16
bgez $a0, 16
# CHECK-NEXT: bge $a0, $zero, 16
# CHECK-NEXT: bgez $a0, 16