py/asmarm: Give a proper name to the temporary register.

This commit performs a small refactoring on the Arm native emitter, by
renaming all but one instance of ASM_ARM_REG_R8 into REG_TEMP.

ASM_ARM_REG_R8 is the temporary register used by the emitter when
operations cannot overwrite the value of a particular register and some
extra storage is needed.

Signed-off-by: Alessandro Gatti <[email protected]>

Author: agatti

py/asmarm.c

@@ -36,6 +36,8 @@
 
 #include "py/asmarm.h"
 
+#define REG_TEMP ASM_ARM_REG_R8
+
 #define SIGNED_FIT24(x) (((x) & 0xff800000) == 0) || (((x) & 0xff000000) == 0xff000000)
 
 // Insert word into instruction flow
@@ -171,8 +173,8 @@ void asm_arm_entry(asm_arm_t *as, int num_locals) {
         if (as->stack_adjust < 0x100) {
             emit_al(as, asm_arm_op_sub_imm(ASM_ARM_REG_SP, ASM_ARM_REG_SP, as->stack_adjust));
         } else {
-            asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, as->stack_adjust);
-            emit_al(as, asm_arm_op_sub_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, ASM_ARM_REG_R8));
+            asm_arm_mov_reg_i32_optimised(as, REG_TEMP, as->stack_adjust);
+            emit_al(as, asm_arm_op_sub_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, REG_TEMP));
         }
     }
 }
@@ -182,8 +184,8 @@ void asm_arm_exit(asm_arm_t *as) {
         if (as->stack_adjust < 0x100) {
             emit_al(as, asm_arm_op_add_imm(ASM_ARM_REG_SP, ASM_ARM_REG_SP, as->stack_adjust));
         } else {
-            asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, as->stack_adjust);
-            emit_al(as, asm_arm_op_add_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, ASM_ARM_REG_R8));
+            asm_arm_mov_reg_i32_optimised(as, REG_TEMP, as->stack_adjust);
+            emit_al(as, asm_arm_op_add_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, REG_TEMP));
         }
     }
 
@@ -293,10 +295,10 @@ void asm_arm_orr_reg_reg_reg(asm_arm_t *as, uint rd, uint rn, uint rm) {
 
 void asm_arm_mov_reg_local_addr(asm_arm_t *as, uint rd, int local_num) {
     if (local_num >= 0x40) {
-        // mov r8, #local_num*4
-        // add rd, sp, r8
-        asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, local_num << 2);
-        emit_al(as, asm_arm_op_add_reg(rd, ASM_ARM_REG_SP, ASM_ARM_REG_R8));
+        // mov temp, #local_num*4
+        // add rd, sp, temp
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, local_num << 2);
+        emit_al(as, asm_arm_op_add_reg(rd, ASM_ARM_REG_SP, REG_TEMP));
     } else {
         // add rd, sp, #local_num*4
         emit_al(as, asm_arm_op_add_imm(rd, ASM_ARM_REG_SP, local_num << 2));
@@ -338,10 +340,10 @@ void asm_arm_ldr_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offse
         // ldr rd, [rn, #off]
         emit_al(as, 0x5900000 | (rn << 16) | (rd << 12) | byte_offset);
     } else {
-        // mov r8, #off
-        // ldr rd, [rn, r8]
-        asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, byte_offset);
-        emit_al(as, 0x7900000 | (rn << 16) | (rd << 12) | ASM_ARM_REG_R8);
+        // mov temp, #off
+        // ldr rd, [rn, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x7900000 | (rn << 16) | (rd << 12) | REG_TEMP);
     }
 }
 
@@ -352,19 +354,19 @@ void asm_arm_ldrh_reg_reg(asm_arm_t *as, uint rd, uint rn) {
 
 void asm_arm_ldrh_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
     // ldrh doesn't support scaled register index
-    emit_al(as, 0x1a00080 | (ASM_ARM_REG_R8 << 12) | rn); // mov r8, rn, lsl #1
-    emit_al(as, 0x19000b0 | (rm << 16) | (rd << 12) | ASM_ARM_REG_R8); // ldrh rd, [rm, r8];
+    emit_al(as, 0x1a00080 | (REG_TEMP << 12) | rn); // mov temp, rn, lsl #1
+    emit_al(as, 0x19000b0 | (rm << 16) | (rd << 12) | REG_TEMP); // ldrh rd, [rm, temp];
 }
 
 void asm_arm_ldrh_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset) {
     if (byte_offset < 0x100) {
         // ldrh rd, [rn, #off]
         emit_al(as, 0x1d000b0 | (rn << 16) | (rd << 12) | ((byte_offset & 0xf0) << 4) | (byte_offset & 0xf));
     } else {
-        // mov r8, #off
-        // ldrh rd, [rn, r8]
-        asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, byte_offset);
-        emit_al(as, 0x19000b0 | (rn << 16) | (rd << 12) | ASM_ARM_REG_R8);
+        // mov temp, #off
+        // ldrh rd, [rn, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x19000b0 | (rn << 16) | (rd << 12) | REG_TEMP);
     }
 }
 
@@ -388,10 +390,10 @@ void asm_arm_str_reg_reg_offset(asm_arm_t *as, uint rd, uint rm, uint byte_offse
         // str rd, [rm, #off]
         emit_al(as, 0x5800000 | (rm << 16) | (rd << 12) | byte_offset);
     } else {
-        // mov r8, #off
-        // str rd, [rm, r8]
-        asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, byte_offset);
-        emit_al(as, 0x7800000 | (rm << 16) | (rd << 12) | ASM_ARM_REG_R8);
+        // mov temp, #off
+        // str rd, [rm, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x7800000 | (rm << 16) | (rd << 12) | REG_TEMP);
     }
 }
 
@@ -412,8 +414,8 @@ void asm_arm_str_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
 
 void asm_arm_strh_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
     // strh doesn't support scaled register index
-    emit_al(as, 0x1a00080 | (ASM_ARM_REG_R8 << 12) | rn); // mov r8, rn, lsl #1
-    emit_al(as, 0x18000b0 | (rm << 16) | (rd << 12) | ASM_ARM_REG_R8); // strh rd, [rm, r8]
+    emit_al(as, 0x1a00080 | (REG_TEMP << 12) | rn); // mov temp, rn, lsl #1
+    emit_al(as, 0x18000b0 | (rm << 16) | (rd << 12) | REG_TEMP); // strh rd, [rm, temp]
 }
 
 void asm_arm_strb_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {