release/19.x: [RISCV] Don't delete all fixups in RISCVMCCodeEmitter::expandLongCondBr. (#109513)

[llvmbot]

Backport c3d3cef

Requested by: @topperc

[llvmbot]

@wangpc-pp What do you think about merging this PR to the release branch?

[llvmbot]

@llvm/pr-subscribers-mc

Author: None (llvmbot)

Changes

Backport c3d3cef

Requested by: @topperc

---

Full diff: https://github.com/llvm/llvm-project/pull/114089.diff

2 Files Affected:

• (modified) llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp (+6-1)
• (modified) llvm/test/MC/RISCV/rv64-relax-all.s (+6)

diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
index 0863345b0c6dc6..c9636b2c702508 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
@@ -283,13 +283,18 @@ void RISCVMCCodeEmitter::expandLongCondBr(const MCInst &MI,
     Offset = 4;
   }
 
+  // Save the number fixups.
+  size_t FixupStartIndex = Fixups.size();
+
   // Emit an unconditional jump to the destination.
   MCInst TmpInst =
       MCInstBuilder(RISCV::JAL).addReg(RISCV::X0).addOperand(SrcSymbol);
   uint32_t Binary = getBinaryCodeForInstr(TmpInst, Fixups, STI);
   support::endian::write(CB, Binary, llvm::endianness::little);
 
-  Fixups.clear();
+  // Drop any fixup added so we can add the correct one.
+  Fixups.resize(FixupStartIndex);
+
   if (SrcSymbol.isExpr()) {
     Fixups.push_back(MCFixup::create(Offset, SrcSymbol.getExpr(),
                                      MCFixupKind(RISCV::fixup_riscv_jal),
diff --git a/llvm/test/MC/RISCV/rv64-relax-all.s b/llvm/test/MC/RISCV/rv64-relax-all.s
index 70a3f77540c997..6705d6ecfb5b62 100644
--- a/llvm/test/MC/RISCV/rv64-relax-all.s
+++ b/llvm/test/MC/RISCV/rv64-relax-all.s
@@ -14,3 +14,9 @@ c.beqz a0, NEAR
 # INSTR:           c.j    0x0 <NEAR>
 # RELAX-INSTR:     jal    zero, 0x0 <NEAR>
 c.j NEAR
+
+bnez s0, .foo
+j    .foo
+beqz s0, .foo
+.foo:
+ret

[llvmbot]

@llvm/pr-subscribers-backend-risc-v

Author: None (llvmbot)

Changes

Backport c3d3cef

Requested by: @topperc

---

Full diff: https://github.com/llvm/llvm-project/pull/114089.diff

2 Files Affected:

• (modified) llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp (+6-1)
• (modified) llvm/test/MC/RISCV/rv64-relax-all.s (+6)

diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
index 0863345b0c6dc6..c9636b2c702508 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
@@ -283,13 +283,18 @@ void RISCVMCCodeEmitter::expandLongCondBr(const MCInst &MI,
     Offset = 4;
   }
 
+  // Save the number fixups.
+  size_t FixupStartIndex = Fixups.size();
+
   // Emit an unconditional jump to the destination.
   MCInst TmpInst =
       MCInstBuilder(RISCV::JAL).addReg(RISCV::X0).addOperand(SrcSymbol);
   uint32_t Binary = getBinaryCodeForInstr(TmpInst, Fixups, STI);
   support::endian::write(CB, Binary, llvm::endianness::little);
 
-  Fixups.clear();
+  // Drop any fixup added so we can add the correct one.
+  Fixups.resize(FixupStartIndex);
+
   if (SrcSymbol.isExpr()) {
     Fixups.push_back(MCFixup::create(Offset, SrcSymbol.getExpr(),
                                      MCFixupKind(RISCV::fixup_riscv_jal),
diff --git a/llvm/test/MC/RISCV/rv64-relax-all.s b/llvm/test/MC/RISCV/rv64-relax-all.s
index 70a3f77540c997..6705d6ecfb5b62 100644
--- a/llvm/test/MC/RISCV/rv64-relax-all.s
+++ b/llvm/test/MC/RISCV/rv64-relax-all.s
@@ -14,3 +14,9 @@ c.beqz a0, NEAR
 # INSTR:           c.j    0x0 <NEAR>
 # RELAX-INSTR:     jal    zero, 0x0 <NEAR>
 c.j NEAR
+
+bnez s0, .foo
+j    .foo
+beqz s0, .foo
+.foo:
+ret

[wangpc-pp]

LGTM as it fixes a bug that exists for a long time.

[github-actions]

@topperc (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.