tor-browser

commit 4c851cb40c568abf19267fe97d044748a11eef83
parent feab854a48140a2489368bc0c7770f30292dd030
Author: Rong "Mantle" Bao <webmaster@csmantle.top>
Date:   Thu, 18 Dec 2025 15:12:39 +0000

Bug 2003226 - [riscv64] Account for jal sequence length when extracting slow call marker. r=nbp,rhunt

Differential Revision: https://phabricator.services.mozilla.com/D274548

Diffstat:
M
js/src/jit/riscv64/MacroAssembler-riscv64.cpp
 | 
16
+++++++++++++++-

1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/js/src/jit/riscv64/MacroAssembler-riscv64.cpp b/js/src/jit/riscv64/MacroAssembler-riscv64.cpp
@@ -4680,8 +4680,22 @@ const int32_t SlowCallMarker = 0x8093;  // addi ra, ra, 0
 void MacroAssembler::wasmCheckSlowCallsite(Register ra_, Label* notSlow,
                                            Register temp1, Register temp2) {
   MOZ_ASSERT(ra_ != temp2);
+
+  UseScratchRegisterScope temps(*this);
+  // temp1 aliases ra_, so allocating a new register.
+  const Register scratchMarker = temps.Acquire();
+  move32(Imm32(SlowCallMarker), scratchMarker);
+
+  Label slow;
+  // Handle `jalr; (ra_ here) marker`.
   load32(Address(ra_, 0), temp2);
-  branch32(Assembler::NotEqual, temp2, Imm32(SlowCallMarker), notSlow);
+  branch32(Assembler::Equal, temp2, scratchMarker, &slow);
+  // Handle `jal; (ra_ here) nop; marker`.
+  // See also: AssemblerRISCVI::jal(Register rd, int32_t imm21); Bug 1996840
+  branch32(Assembler::NotEqual, temp2, Imm32(kNopByte), notSlow);
+  load32(Address(ra_, 4), temp2);
+  branch32(Assembler::NotEqual, temp2, scratchMarker, notSlow);
+  bind(&slow);
 }
 
 CodeOffset MacroAssembler::wasmMarkedSlowCall(const wasm::CallSiteDesc& desc,