From 3faf2d124906caae80809192a0d8305ebfa88f45 Mon Sep 17 00:00:00 2001
From: Basilisk-Dev <basiliskdev@protonmail.com>
Date: Wed, 22 Apr 2026 23:39:10 -0400
Subject: [PATCH] Issue #3049 - Add LoongArch minimal JIT multiply support

---
 .../tests/basic/loongarch-minimal-jit.js      | 13 +++++++
 js/src/jit/LoongArchMinimalJit.cpp            | 37 +++++++++++++++++--
 2 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/js/src/jit-test/tests/basic/loongarch-minimal-jit.js b/js/src/jit-test/tests/basic/loongarch-minimal-jit.js
index 1c67f3cb16..884b7b4ed6 100644
--- a/js/src/jit-test/tests/basic/loongarch-minimal-jit.js
+++ b/js/src/jit-test/tests/basic/loongarch-minimal-jit.js
@@ -80,6 +80,14 @@ function unsignedRightShift(a, b) {
   return a >>> b;
 }
 
+function multiply(a, b) {
+  return a * b;
+}
+
+function multiplyZero(a) {
+  return a * 0;
+}
+
 function assignArg(a, b) {
   a = a < b;
   return a;
@@ -150,6 +158,11 @@ assertEq(leftShift(1, 33), 2);
 assertEq(rightShift(-8, 1), -4);
 assertEq(unsignedRightShift(-1, 1), 2147483647);
 assertEq(unsignedRightShift(-1, 0), 4294967295);
+assertEq(multiply(6, 7), 42);
+assertEq(multiply(-3, 7), -21);
+assertEq(multiply(1073741824, 4), 4294967296);
+assertEq(multiplyZero(3), 0);
+assertEq(1 / multiplyZero(-3), -Infinity);
 assertEq(assignArg(2, 3), true);
 assertEq(assignArg(3, 2), false);
 assertEq(boolToNumeric(2, 3), 1);
diff --git a/js/src/jit/LoongArchMinimalJit.cpp b/js/src/jit/LoongArchMinimalJit.cpp
index 962e65c185..23fe000fdc 100644
--- a/js/src/jit/LoongArchMinimalJit.cpp
+++ b/js/src/jit/LoongArchMinimalJit.cpp
@@ -349,6 +349,31 @@ class MinimalLoongArchCompiler
         MOZ_CRASH("bad shift opcode");
     }
 
+    bool emitMul(LoongArchReg lhs, LoongArchReg rhs, LoongArchReg out) {
+        if (!emit(EncodeThreeReg(0x001c8000, WideScratch, lhs, rhs)))
+            return false;
+        if (!emit(EncodeThreeReg(0x001c0000, out, lhs, rhs)))
+            return false;
+        if (!emitLoadImm32(NarrowScratch, 31))
+            return false;
+        if (!emit(EncodeThreeReg(0x00180000, NarrowScratch, out, NarrowScratch)))
+            return false;
+        if (!emitFailureBranch())
+            return false;
+
+        if (!emitEq(out, zero, WideScratch, false))
+            return false;
+        if (!emit(EncodeThreeReg(0x00150000, NarrowScratch, lhs, rhs)))
+            return false;
+        if (!emit(EncodeThreeReg(0x00120000, NarrowScratch, NarrowScratch, zero)))
+            return false;
+        if (!emit(EncodeThreeReg(0x00148000, WideScratch, WideScratch, NarrowScratch)))
+            return false;
+        if (!emitMove(NarrowScratch, zero))
+            return false;
+        return emitFailureBranch();
+    }
+
     bool emitBranch(BranchKind kind, LoongArchReg reg, uint32_t targetPcOffset) {
         BranchPatch patch = { wordCount_, targetPcOffset, kind, reg };
         if (!branchPatches_.append(patch))
@@ -608,7 +633,8 @@ class MinimalLoongArchCompiler
               case JSOP_NOP:
                 break;
               case JSOP_ADD:
-              case JSOP_SUB: {
+              case JSOP_SUB:
+              case JSOP_MUL: {
                 StackValue rhs;
                 StackValue lhs;
                 if (!pop(&rhs) || !pop(&lhs))
@@ -616,8 +642,13 @@ class MinimalLoongArchCompiler
                 if (!IsNumericKind(lhs.kind) || !IsNumericKind(rhs.kind))
                     return false;
                 LoongArchReg out = allocStackReg();
-                if (!emitCheckedBinary(op, lhs.reg, rhs.reg, out))
-                    return false;
+                if (op == JSOP_MUL) {
+                    if (!emitMul(lhs.reg, rhs.reg, out))
+                        return false;
+                } else {
+                    if (!emitCheckedBinary(op, lhs.reg, rhs.reg, out))
+                        return false;
+                }
                 stack_[stackDepth_++] = { out, MinimalValueKind::Int32 };
                 break;
               }