ref: 355f73cb919d009d7527b5083ae8341f0ceea97d
dir: /src/cmd/cc/cc2/target/qbe/optm.c/
#include <stddef.h> #include <scc/scc.h> #include "../../cc2.h" Node * optm_dep(Node *np) { int op = np->op; Node *p, *dst, *next = np->next; Symbol *sym, *osym; switch (op) { case OEFUN: /* * In QBE we need at the end of a basic block * a jump, so we have to ensure that the last * statement of the function is a ret, a jmp * or a branch. In the same way, QBE does * not accept labels at the end of a function * (ONOP is used for labels) so we have to add * a ret there, and in the case of branches * we need a label for the next statement */ op = (np->prev) ? np->prev->op : 0; if (!op || op == ONOP || op == OBRANCH || (op != ORET && op != OJMP)) addstmt(node(ORET), KEEPCUR); break; case OBRANCH: if (!next->label) { sym = getsym(TMPSYM); sym->kind = SLABEL; next->label = sym; } case OJMP: for (;;) { dst = np->u.sym->u.stmt; if (dst->op != OJMP) break; np->u.sym = dst->u.sym; } for (p = np->next; p; p = p->next) { if (p == dst) return NULL; if (p->op == ONOP || p->op == OBLOOP || p->op == OELOOP) { continue; } break; } break; } return np; }