Merge pull request sysprog21#479 from vacantron/fix/jalr

Fix unexpected "JALR" behavior in JIT
vestata · Aug 21, 2024 · c21585a · c21585a
2 parents aa75400 + 09d5d00
commit c21585a
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Showing 4 changed files with 31 additions and 18 deletions.
diff --git a/build/fibonacci.elf b/build/fibonacci.elf
diff --git a/src/rv32_template.c b/src/rv32_template.c
@@ -270,14 +270,17 @@ RVOP(
         goto end_op;
     },
     GEN({
-        cond, rd;
-        map, VR0, rd;
-        ldimm, VR0, pc, 4;
-        end;
-        rald, VR1, rs1;
-        mov, VR1, TMP;
+        /* The register which stores the indirect address needs to be loaded
+         * first to avoid being overriden by other operation.
+         */
+        rald, VR0, rs1;
+        mov, VR0, TMP;
         alu32imm, 32, 0x81, 0, TMP, imm;
         alu32imm, 32, 0x81, 4, TMP, ~1U;
+        cond, rd;
+        map, VR1, rd;
+        ldimm, VR1, pc, 4;
+        end;
         break;
         predict;
         st, S32, TMP, PC;
@@ -2360,10 +2363,13 @@ RVOP(
         goto end_op;
     },
     GEN({
-        map, VR0, rv_reg_ra;
-        ldimm, VR0, pc, 2;
-        rald, VR1, rs1;
-        mov, VR1, TMP;
+        /* The register which stores the indirect address needs to be loaded
+         * first to avoid being overriden by other operation.
+         */
+        rald, VR0, rs1;
+        mov, VR0, TMP;
+        map, VR1, rv_reg_ra;
+        ldimm, VR1, pc, 2;
         break;
         predict;
         st, S32, TMP, PC;

diff --git a/src/t2c_template.c b/src/t2c_template.c
@@ -90,13 +90,17 @@ FORCE_INLINE void t2c_jit_cache_helper(LLVMBuilderRef *builder,
 }
 
 T2C_OP(jalr, {
+    /* The register which stores the indirect address needs to be loaded first
+     * to avoid being overriden by other operation.
+     */
+    T2C_LLVM_GEN_LOAD_VMREG(rs1, 32, t2c_gen_rs1_addr(start, builder, ir));
+    val_rs1 = T2C_LLVM_GEN_ALU32_IMM(Add, val_rs1, ir->imm);
+    val_rs1 = T2C_LLVM_GEN_ALU32_IMM(And, val_rs1, ~1U);
+
     if (ir->rd)
         T2C_LLVM_GEN_STORE_IMM32(*builder, ir->pc + 4,
                                  t2c_gen_rd_addr(start, builder, ir));
 
-    T2C_LLVM_GEN_LOAD_VMREG(rs1, 32, t2c_gen_rs1_addr(start, builder, ir));
-    val_rs1 = T2C_LLVM_GEN_ALU32_IMM(Add, val_rs1, ir->imm);
-    val_rs1 = T2C_LLVM_GEN_ALU32_IMM(And, val_rs1, ~1U);
     t2c_jit_cache_helper(builder, start, val_rs1, rv, ir);
 })
 
@@ -744,9 +748,12 @@ T2C_OP(cebreak, {
 })
 
 T2C_OP(cjalr, {
+    /* The register which stores the indirect address needs to be loaded first
+     * to avoid being overriden by other operation.
+     */
+    T2C_LLVM_GEN_LOAD_VMREG(rs1, 32, t2c_gen_rs1_addr(start, builder, ir));
     T2C_LLVM_GEN_STORE_IMM32(*builder, ir->pc + 2,
                              t2c_gen_ra_addr(start, builder, ir));
-    T2C_LLVM_GEN_LOAD_VMREG(rs1, 32, t2c_gen_rs1_addr(start, builder, ir));
     t2c_jit_cache_helper(builder, start, val_rs1, rv, ir);
 })
 

diff --git a/tests/fibonacci.s b/tests/fibonacci.s
@@ -7,12 +7,12 @@ fib:
     sw s1, 4(sp)
     mv s0, a0
     addi a0, a0, -1
-    la t0, fib
-    jalr ra, 0(t0)
+    la ra, fib
+    jalr ra, 0(ra)
     mv s1, a0
     addi a0, s0, -2
-    la t0, fib
-    jalr ra, 0(t0)
+    la ra, fib
+    jalr ra, 0(ra)
     add a0, s1, a0
     lw ra, 12(sp)
     lw s0, 8(sp)