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https://github.com/golang/go
synced 2024-11-12 09:10:21 -07:00
cleaned up cgen() to be a bit more straightforward.
R=rsc APPROVED=rsc DELTA=104 (46 added, 56 deleted, 2 changed) OCL=35392 CL=35394
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c62b3265a7
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@ -76,46 +76,6 @@ cgen(Node *n, Node *res)
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goto ret;
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}
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if(!res->addable) {
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if(n->ullman > res->ullman) {
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regalloc(&n1, n->type, res);
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cgen(n, &n1);
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if(n1.ullman > res->ullman) {
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dump("n1", &n1);
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dump("res", res);
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fatal("loop in cgen");
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}
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cgen(&n1, res);
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regfree(&n1);
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goto ret;
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}
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if(res->ullman >= UINF)
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goto gen;
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a = optoas(OAS, res->type);
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if(sudoaddable(a, res, &addr, &w)) {
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if(n->op != OREGISTER) {
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regalloc(&n2, res->type, N);
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cgen(n, &n2);
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p1 = gins(a, &n2, N);
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regfree(&n2);
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} else
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p1 = gins(a, n, N);
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p1->to = addr;
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if(debug['g'])
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print("%P [ignore previous line]\n", p1);
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sudoclean();
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goto ret;
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}
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gen:
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igen(res, &n1, N);
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cgen(n, &n1);
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regfree(&n1);
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goto ret;
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}
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// update addressability for string, slice
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// can't do in walk because n->left->addable
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// changes if n->left is an escaping local variable.
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@ -130,8 +90,9 @@ cgen(Node *n, Node *res)
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break;
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}
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if(n->addable) {
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if (n->op == OREGISTER || is64(n->type) || is64(res->type)) {
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// if both are addressable, move
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if(n->addable && res->addable) {
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if (is64(n->type) || is64(res->type) || n->op == OREGISTER || res->op == OREGISTER) {
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gmove(n, res);
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} else {
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regalloc(&n1, n->type, N);
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@ -142,6 +103,51 @@ cgen(Node *n, Node *res)
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goto ret;
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}
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// if both are not addressable, use a temporary.
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if(!n->addable && !res->addable) {
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// could use regalloc here sometimes,
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// but have to check for ullman >= UINF.
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tempname(&n1, n->type);
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cgen(n, &n1);
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cgen(&n1, res);
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return;
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}
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// if result is not addressable directly but n is,
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// compute its address and then store via the address.
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if(!res->addable) {
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igen(res, &n1, N);
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cgen(n, &n1);
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regfree(&n1);
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return;
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}
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// if n is sudoaddable generate addr and move
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if (!is64(n->type) && !is64(res->type)) {
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a = optoas(OAS, n->type);
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if(sudoaddable(a, n, &addr, &w)) {
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if (res->op != OREGISTER) {
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regalloc(&n2, res->type, N);
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p1 = gins(a, N, &n2);
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p1->from = addr;
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if(debug['g'])
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print("%P [ignore previous line]\n", p1);
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gmove(&n2, res);
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regfree(&n2);
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} else {
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p1 = gins(a, N, res);
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p1->from = addr;
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if(debug['g'])
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print("%P [ignore previous line]\n", p1);
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}
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sudoclean();
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goto ret;
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}
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}
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// otherwise, the result is addressable but n is not.
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// let's do some computation.
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nl = n->left;
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nr = n->right;
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@ -172,22 +178,6 @@ cgen(Node *n, Node *res)
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cgen64(n, res);
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return;
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}
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} else {
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a = optoas(OAS, n->type);
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if(sudoaddable(a, n, &addr, &w)) {
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if(res->op == OREGISTER) {
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p1 = gins(a, N, res);
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p1->from = addr;
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} else {
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regalloc(&n2, n->type, N);
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p1 = gins(a, N, &n2);
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p1->from = addr;
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gins(a, &n2, res);
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regfree(&n2);
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}
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sudoclean();
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goto ret;
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}
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}
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switch(n->op) {
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