scc

Simple C99 Compiler
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commit 37382404ddb754527377141d0e17fd9df287f643
parent 0221fe4f3687d2482eceacdc21ae7389f4634640
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Fri, 20 Mar 2015 17:04:47 -0400

Add used field in Nodes of cc2

This field allows to know when a node was already used and
the register used by it can be reused.

Diffstat:
cc2/cc2.h | 1+
cc2/cgen.c | 15+++++++++------
2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/cc2/cc2.h b/cc2/cc2.h @@ -81,6 +81,7 @@ struct node { uint8_t addable; uint8_t reg; Symbol *sym; + bool used : 1; struct node *left, *right; }; diff --git a/cc2/cgen.c b/cc2/cgen.c @@ -86,20 +86,22 @@ allocreg(uint8_t size) { static uint8_t reg8[] = {A, B, C, D, E, H, L, IYL, IY, 0}; static uint8_t reg16[] = {BC, DE, IY, 0}; - uint8_t *bp, c; + Node *np; + uint8_t *ary, *bp, c; switch (size) { case 1: - bp = reg8; + ary = reg8; break; case 2: - bp = reg16; + ary = reg16; break; default: abort(); } - while (c = *bp++) { - if (reguse[c]) + for (bp = ary; c = *bp; ++bp) { + np = reguse[c]; + if (np && !np->used) continue; return c; } @@ -299,6 +301,7 @@ add(Node *np) add1: move(rp, np); code((np->op == OADD) ? ADD : SUB, lp, rp); + lp->used = rp->used = 1; np->op = REG; np->reg = A; reguse[A] = np; @@ -315,7 +318,6 @@ assign(Node *np) Symbol *sym = lp->sym; assert(rp->op == REG); - /* TODO: what happens with the previous register? */ switch (np->type.size) { case 1: switch (lp->op) { @@ -337,6 +339,7 @@ assign(Node *np) abort(); } + lp->used = 1; np->op = REG; np->reg = rp->reg; }