From bfa3551dd3ac2d8aba42f2c8cb296ea0494e679a Mon Sep 17 00:00:00 2001
From: wanglei <wanglei@loongson.cn>
Date: Fri, 18 Nov 2022 16:33:49 +0800
Subject: [PATCH] [LoongArch] Implement assembler branches pseudo instructions

These instructions always output the canonical mnemonic. 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).

Reviewed By: xen0n

Differential Revision: https://reviews.llvm.org/D138100
---
 .../Target/LoongArch/LoongArchInstrInfo.td    | 22 +++++++++++++++++++
 llvm/test/MC/LoongArch/Macros/aliases-br.s    | 18 +++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 llvm/test/MC/LoongArch/Macros/aliases-br.s

diff --git a/llvm/lib/Target/LoongArch/LoongArchInstrInfo.td b/llvm/lib/Target/LoongArch/LoongArchInstrInfo.td
index 2a8fc40f984a..885c4d75f0b9 100644
--- a/llvm/lib/Target/LoongArch/LoongArchInstrInfo.td
+++ b/llvm/lib/Target/LoongArch/LoongArchInstrInfo.td
@@ -1348,6 +1348,28 @@ 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.
+def : InstAlias<"bgt $rj, $rd, $imm16",
+                (BLT GPR:$rd, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
+def : InstAlias<"bgtu $rj, $rd, $imm16",
+                (BLTU GPR:$rd, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
+def : InstAlias<"ble $rj, $rd, $imm16",
+                (BGE GPR:$rd, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
+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>;
+def : InstAlias<"bgtz $rj, $imm16",
+                (BLT R0, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
+def : InstAlias<"blez $rj, $imm16",
+                (BGE R0, GPR:$rj, simm16_lsl2_br:$imm16), 0>;
+def : InstAlias<"bgez $rd, $imm16",
+                (BGE GPR:$rd, R0, simm16_lsl2_br:$imm16), 0>;
+
 //===----------------------------------------------------------------------===//
 // Basic Floating-Point Instructions
 //===----------------------------------------------------------------------===//
diff --git a/llvm/test/MC/LoongArch/Macros/aliases-br.s b/llvm/test/MC/LoongArch/Macros/aliases-br.s
new file mode 100644
index 000000000000..e8d85bdec763
--- /dev/null
+++ b/llvm/test/MC/LoongArch/Macros/aliases-br.s
@@ -0,0 +1,18 @@
+# RUN: llvm-mc --triple=loongarch64 %s | FileCheck %s
+
+bgt   $a1, $a0, 16
+# CHECK:      blt     $a0, $a1, 16
+bgtu  $a1, $a0, 16
+# CHECK-NEXT: bltu    $a0, $a1, 16
+ble   $a1, $a0, 16
+# CHECK-NEXT: bge     $a0, $a1, 16
+bleu  $a1, $a0, 16
+# CHECK-NEXT: bgeu    $a0, $a1, 16
+bltz   $a0, 16
+# CHECK-NEXT: blt     $a0, $zero, 16
+bgtz   $a0, 16
+# CHECK-NEXT: blt     $zero, $a0, 16
+blez   $a0, 16
+# CHECK-NEXT: bge     $zero, $a0, 16
+bgez   $a0, 16
+# CHECK-NEXT: bge     $a0, $zero, 16