Separate const-vregs management

And share a register if the value is same.
tyfkda · Oct 13, 2023 · 054fda0 · 054fda0
1 parent 83183e2
commit 054fda0
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Showing 6 changed files with 40 additions and 25 deletions.
diff --git a/src/_debug/dump_ir.c b/src/_debug/dump_ir.c
@@ -169,8 +169,6 @@ static void dump_func_ir(Function *func) {
       case LI_SPILL:
         fprintf(fp, "  V%3d (flag=%x): live %3d - %3d (spilled, offset=%d)\n", li->virt, vreg->flag, li->start, li->end, vreg->frame.offset);
         break;
-      case LI_CONST:
-        continue;
       }
     }
   }

diff --git a/src/cc/backend/codegen.c b/src/cc/backend/codegen.c
@@ -737,8 +737,8 @@ static void map_virtual_to_physical_registers(RegAlloc *ra) {
     VReg *vreg = ra->vregs->data[i];
     if (vreg == NULL)
       continue;
-    if (!(vreg->flag & VRF_CONST))
-      vreg->phys = ra->intervals[vreg->virt].phys;
+    assert(!(vreg->flag & VRF_CONST) && vreg->virt >= 0);
+    vreg->phys = ra->intervals[vreg->virt].phys;
   }
 }
 

diff --git a/src/cc/backend/ir.c b/src/cc/backend/ir.c
@@ -35,9 +35,7 @@ static IR *new_ir(enum IrKind kind) {
 }
 
 VReg *new_const_vreg(int64_t value, enum VRegSize vsize, int vflag) {
-  VReg *vreg = reg_alloc_spawn(curra, vsize, vflag | VRF_CONST);
-  vreg->fixnum = value;
-  return vreg;
+  return reg_alloc_spawn_const(curra, value, vsize, vflag);
 }
 
 VReg *new_ir_bop(enum IrKind kind, VReg *opr1, VReg *opr2, enum VRegSize vsize) {

diff --git a/src/cc/backend/optimize.c b/src/cc/backend/optimize.c
@@ -155,7 +155,7 @@ static void remove_unused_vregs(RegAlloc *ra, BBContainer *bbcon) {
       VReg *operands[] = {ir->opr1, ir->opr2};
       for (int k = 0; k < 2; ++k) {
         VReg *vreg = operands[k];
-        if (vreg != NULL)
+        if (vreg != NULL && !(vreg->flag & VRF_CONST))
           vreg_read[vreg->virt] = true;
       }
     }

diff --git a/src/cc/backend/regalloc.c b/src/cc/backend/regalloc.c
@@ -16,6 +16,7 @@ RegAlloc *new_reg_alloc(const RegAllocSettings *settings) {
   assert(settings->phys_max < (int)(sizeof(ra->used_reg_bits) * CHAR_BIT));
   ra->settings = settings;
   ra->vregs = new_vector();
+  ra->consts = new_vector();
   ra->intervals = NULL;
   ra->sorted_intervals = NULL;
   ra->used_reg_bits = 0;
@@ -24,19 +25,39 @@ RegAlloc *new_reg_alloc(const RegAllocSettings *settings) {
   return ra;
 }
 
-VReg *reg_alloc_spawn(RegAlloc *ra, enum VRegSize vsize, int vflag) {
-  int vreg_no = ra->vregs->len;
-
+static VReg *alloc_vreg(enum VRegSize vsize, int vflag) {
   VReg *vreg = malloc_or_die(sizeof(*vreg));
-  vreg->virt = vreg_no;
+  vreg->virt = -1;
   vreg->phys = -1;
   vreg->fixnum = 0;
   vreg->vsize = vsize;
   vreg->flag = vflag;
   vreg->reg_param_index = -1;
   vreg->frame.offset = 0;
+  return vreg;
+}
+
+VReg *reg_alloc_spawn(RegAlloc *ra, enum VRegSize vsize, int vflag) {
+  VReg *vreg = alloc_vreg(vsize, vflag);
+  if (!(vflag & VRF_CONST)) {
+    vreg->virt = ra->vregs->len;
+    vec_push(ra->vregs, vreg);
+  } else {
+    vec_push(ra->consts, vreg);
+  }
+  return vreg;
+}
 
-  vec_push(ra->vregs, vreg);
+VReg *reg_alloc_spawn_const(RegAlloc *ra, int64_t value, enum VRegSize vsize, int vflag) {
+  vflag |= VRF_CONST;
+  for (int i = 0; i < ra->consts->len; ++i) {
+    VReg *v = ra->consts->data[i];
+    if (v->fixnum == value && v->vsize == vsize && v->flag == vflag)
+      return v;
+  }
+
+  VReg *vreg = reg_alloc_spawn(ra, vsize, vflag);
+  vreg->fixnum = value;
   return vreg;
 }
 
@@ -385,20 +406,20 @@ static int insert_load_store_spilled_irs(RegAlloc *ra, BBContainer *bbcon) {
         continue;
       }
 
-      if (ir->opr1 != NULL && (flag & 1) != 0 &&
-          !(ir->opr1->flag & VRF_CONST) && (ir->opr1->flag & VRF_SPILLED)) {
+      if (ir->opr1 != NULL && (flag & 1) != 0 && (ir->opr1->flag & VRF_SPILLED)) {
+        assert(!(ir->opr1->flag & VRF_CONST));
         j = insert_tmp_reg(ra, irs, j, ir->opr1);
         ++inserted;
       }
 
-      if (ir->opr2 != NULL && (flag & 2) != 0 &&
-          !(ir->opr2->flag & VRF_CONST) && (ir->opr2->flag & VRF_SPILLED)) {
+      if (ir->opr2 != NULL && (flag & 2) != 0 && (ir->opr2->flag & VRF_SPILLED)) {
+        assert(!(ir->opr2->flag & VRF_CONST));
         j = insert_tmp_reg(ra, irs, j, ir->opr2);
         ++inserted;
       }
 
-      if (ir->dst != NULL && (flag & 4) != 0 &&
-          !(ir->dst->flag & VRF_CONST) && (ir->dst->flag & VRF_SPILLED)) {
+      if (ir->dst != NULL && (flag & 4) != 0 && (ir->dst->flag & VRF_SPILLED)) {
+        assert(!(ir->dst->flag & VRF_CONST));
         j = insert_tmp_reg(ra, irs, j, ir->dst);
         ++inserted;
       }
@@ -424,10 +445,7 @@ void alloc_physical_registers(RegAlloc *ra, BBContainer *bbcon) {
       if (vreg == NULL)
         continue;
 
-      if (vreg->flag & VRF_CONST) {
-        li->state = LI_CONST;
-        continue;
-      }
+      assert(!(vreg->flag & VRF_CONST));
 
       if (vreg->flag & VRF_SPILLED) {
         li->state = LI_SPILL;

diff --git a/src/cc/backend/regalloc.h b/src/cc/backend/regalloc.h
@@ -16,7 +16,6 @@ typedef struct Vector Vector;
 enum LiveIntervalState {
   LI_NORMAL,
   LI_SPILL,
-  LI_CONST,
 };
 
 typedef struct LiveInterval {
@@ -41,7 +40,8 @@ typedef struct RegAllocSettings {
 
 typedef struct RegAlloc {
   const RegAllocSettings *settings;
-  Vector *vregs;  // <VReg*>
+  Vector *vregs;   // <VReg*>, non-const vregs
+  Vector *consts;  // <VReg*>, const vregs
   LiveInterval *intervals;  // size=vregs->len
   LiveInterval **sorted_intervals;
 
@@ -52,4 +52,5 @@ typedef struct RegAlloc {
 
 RegAlloc *new_reg_alloc(const RegAllocSettings *settings);
 VReg *reg_alloc_spawn(RegAlloc *ra, enum VRegSize vsize, int vflag);
+VReg *reg_alloc_spawn_const(RegAlloc *ra, int64_t value, enum VRegSize vsize, int vflag);
 void alloc_physical_registers(RegAlloc *ra, BBContainer *bbcon);