[llvm-branch-commits] [llvm] release/23.x: [SPARC][IAS] Adjust bounds check in %rX name parsing (#218301) (PR #218333)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/218333

Backport e013a0f906630d014e04824681b32daa45812c7c

Requested by: @brad0

>From e90d2f421a38066d2c24102dc091270d029ecb12 Mon Sep 17 00:00:00 2001
From: Koakuma <koachan at protonmail.com>
Date: Mon, 24 Aug 2026 12:07:54 +0700
Subject: [PATCH] [SPARC][IAS] Adjust bounds check in %rX name parsing
 (#218301)

Fix an off-by-one error that results in %r31 being incorrectly rejected.

This was reported by the folks at OpenBSD.

(cherry picked from commit e013a0f906630d014e04824681b32daa45812c7c)
---
 llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp | 2 +-
 llvm/test/MC/Sparc/sparc-alu-instructions.s        | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp b/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
index f6b8e0af67150..bab05f5e0ada8 100644
--- a/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
+++ b/llvm/lib/Target/Sparc/AsmParser/SparcAsmParser.cpp
@@ -1591,7 +1591,7 @@ MCRegister SparcAsmParser::matchRegisterName(const AsmToken &Tok,
   // %r0 - %r31
   int64_t RegNo = 0;
   if (Name.starts_with_insensitive("r") &&
-      !Name.substr(1, 2).getAsInteger(10, RegNo) && RegNo < 31) {
+      !Name.substr(1, 2).getAsInteger(10, RegNo) && RegNo <= 31) {
     RegKind = SparcOperand::rk_IntReg;
     return IntRegs[RegNo];
   }
diff --git a/llvm/test/MC/Sparc/sparc-alu-instructions.s b/llvm/test/MC/Sparc/sparc-alu-instructions.s
index 98a3dc22b7799..903eb52034f61 100644
--- a/llvm/test/MC/Sparc/sparc-alu-instructions.s
+++ b/llvm/test/MC/Sparc/sparc-alu-instructions.s
@@ -9,6 +9,8 @@
         add %r8, %r9, %l0
         ! CHECK: add %o0, 10,  %l0    ! encoding: [0xa0,0x02,0x20,0x0a]
         add %o0, 10, %l0
+        ! CHECK: add %g0, %o7, %i7    ! encoding: [0xbe,0x00,0x00,0x0f]
+        add %r0, %r15, %r31
 
         ! CHECK: addcc %g1, %g2, %g3  ! encoding: [0x86,0x80,0x40,0x02]
         addcc %g1, %g2, %g3