new opt pass

build.c

@@ -58,6 +58,7 @@ struct CompileData target_lib_files[] = {
     SP(CT_C, "ir/opt/ll_binary.c"),
     SP(CT_C, "ir/opt/simple_patterns.c"),
     SP(CT_C, "ir/opt/ll_sched.c"),
+    SP(CT_C, "ir/opt/if_opts.c"),
 
     DIR("build/ir/transform"),
     SP(CT_C, "ir/transform/single_assign_conditional.c"),

ir/analysis.c

@@ -243,6 +243,12 @@ bool vx_IrOpType_hasEffect(vx_IrOpType type)
 
 bool vx_IrOp_endsFlow(vx_IrOp *op)
 {
+    if (op->id == VX_IR_OP_IF)
+    {
+        vx_IrBlock* pthen = vx_IrOp_param(op, VX_IR_NAME_COND_THEN)->block;
+        vx_IrBlock* pelse = vx_IrOp_param(op, VX_IR_NAME_COND_ELSE)->block;
+        return vx_IrBlock_endsFlow(pthen) && vx_IrBlock_endsFlow(pelse);
+    }
     return vx_IrOpType__entries[op->id].endsFlow.a;
 }
 

ir/opt.c

@@ -39,6 +39,7 @@ void opt(vx_IrBlock *block) {
     vx_opt_join_compute(block);
     if (vx_g_optconfig.if_eval) {
         vx_opt_reduce_if(block);
+        vx_opt_if_opts(block);
     }
     vx_opt_cmov(block);
     opt_pre(block);

ir/opt.h

@@ -23,6 +23,7 @@ OPT_PASS void vx_opt_cmov(vx_IrBlock *block);
 OPT_PASS void vx_opt_vars(vx_IrBlock *block);
 OPT_PASS void vx_opt_ll_jumps(vx_IrBlock *block);
 OPT_PASS void vx_opt_simple_patterns(vx_IrBlock* block);
+OPT_PASS void vx_opt_if_opts(vx_IrBlock* block);
 
 OPT_PASS void vx_opt_ll_dce(vx_IrBlock *block);
 OPT_PASS void vx_opt_ll_condtailcall(vx_IrBlock *block);

ir/opt/if_opts.c

@@ -0,0 +1,95 @@
+#include "../opt.h"
+
+// TODO: move to ir/transform.c
+static vx_IrVar genIntoVar(vx_IrBlock* block, vx_IrValue val)
+{
+    vx_IrOp* op = vx_IrBlock_addOpBuilding(block);
+    vx_IrOp_init(op, VX_IR_OP_IMM, block);
+    vx_IrBlock* root = vx_IrBlock_root(block);
+    vx_IrVar var = vx_IrBlock_newVar(root, op);
+    vx_IrTypeRef ty = vx_IrValue_type(root, val);
+    vx_IrOp_addOut(op, var, ty.ptr);
+    vx_IrTypeRef_drop(ty);
+    vx_IrOp_addParam_s(op, VX_IR_NAME_VALUE, val);
+    return var;
+}
+
+void vx_opt_if_opts(vx_IrBlock* block)
+{
+    // move code after if statements that partially end flow into the branch that doesn't end flow
+    for (vx_IrOp* op = block->first; op; op = op->next)
+    {
+        if (op->id != VX_IR_OP_IF)
+            continue;
+
+        vx_IrBlock* bthen = vx_IrOp_param(op, VX_IR_NAME_COND_THEN)->block; assert(bthen);
+        vx_IrBlock* belse = vx_IrOp_param(op, VX_IR_NAME_COND_ELSE)->block; assert(belse);
+
+        bool thenEnds = vx_IrBlock_endsFlow(bthen); 
+        bool elseEnds = vx_IrBlock_endsFlow(belse);
+
+        if (thenEnds == elseEnds)
+            continue;
+
+        vx_IrBlock* notEndingBlk = thenEnds ? belse : bthen;
+
+        vx_IrOp* next = op->next;
+        op->next = NULL;
+
+        for (vx_IrOp* o = next; o; o = o->next)
+            o->parent = notEndingBlk;
+
+        {
+            vx_IrOp* tail = vx_IrBlock_tail(notEndingBlk);
+            if (tail == NULL) {
+                notEndingBlk->first = next;
+            } else {
+                tail->next = next;
+            }
+        }
+
+        for (size_t i = 0; i < op->outs_len; i ++)
+            vx_IrBlock_renameVar(notEndingBlk, op->outs[i].var, notEndingBlk->outs[i]);
+
+        break; // there is no next anymore 
+    }
+
+    vx_opt_ll_dce(block); // it says ll but also works in ssa 
+
+    for (vx_IrOp* op = block->first; op; op = op->next)
+    {
+        if (op->id != VX_IR_OP_IF)
+            continue;
+
+        vx_IrBlock* bthen = vx_IrOp_param(op, VX_IR_NAME_COND_THEN)->block;
+        vx_IrBlock* belse = vx_IrOp_param(op, VX_IR_NAME_COND_ELSE)->block;
+
+        vx_IrOp* thenLast = vx_IrBlock_tail(bthen);
+        vx_IrOp* elseLast = vx_IrBlock_tail(belse);
+
+        if (!thenLast) continue;
+        if (!elseLast) continue;
+        if (thenLast->id != VX_IR_OP_RETURN) continue;
+        if (elseLast->id != VX_IR_OP_RETURN) continue;
+
+        vx_IrOp* retInst = vx_IrBlock_insertOpBuildingAfter(op);
+        vx_IrOp_init(retInst, VX_IR_OP_RETURN, block);
+
+        vx_IrBlock* root = vx_IrBlock_root(block);
+        size_t numRets = root->outs_len;
+        for (size_t i = 0; i < numRets; i ++)
+        {
+            vx_IrBlock_addOut(bthen, genIntoVar(bthen, thenLast->args[i]));
+            vx_IrBlock_addOut(belse, genIntoVar(belse, elseLast->args[i]));
+
+            vx_IrVar va = vx_IrBlock_newVar(root, op);
+            vx_IrOp_addOut(op, va, vx_IrBlock_typeofVar(root, root->outs[i]));
+            vx_IrOp_addArg(retInst, VX_IR_VALUE_VAR(va));
+        }
+
+        vx_IrOp_remove(thenLast);
+        vx_IrOp_remove(elseLast);
+
+        break; // the next op is going to be the return we just inserted
+    }
+}