diff options
| -rw-r--r-- | amd64/emit.c | 39 | ||||
| -rw-r--r-- | ir.h | 1 | ||||
| -rw-r--r-- | regalloc.c | 4 |
3 files changed, 34 insertions, 10 deletions
diff --git a/amd64/emit.c b/amd64/emit.c index 9c699bd..7e9bbd3 100644 --- a/amd64/emit.c +++ b/amd64/emit.c @@ -813,12 +813,17 @@ emitbranch(uchar **pcode, struct block *blk) } static void -calleesave(uchar **pcode, struct function *fn) +calleesave(int *npush, uchar **pcode, struct function *fn) { - if (bstest(fn->regusage, RBX)) Xpush(pcode, RBX); + if (bstest(fn->regusage, RBX)) { + Xpush(pcode, RBX); + ++*npush; + } for (int r = R12; r <= R15; ++r) - if (bstest(fn->regusage, r)) - Xpush(pcode, r); + if (bstest(fn->regusage, r)) { + Xpush(pcode, r); + ++*npush; + } } static void @@ -832,7 +837,7 @@ calleerestore(uchar **pcode, struct function *fn) /* align code using NOPs */ static void -aligncode(uchar **pcode, int align) +nops(uchar **pcode, int align) { int rem; while ((rem = (*pcode - objout.textbegin) & (align - 1)) != 0) { @@ -857,6 +862,8 @@ emitbin(struct function *fn) struct block *blk; uchar **pcode = &objout.code; uchar *start; + int npush = 0; + bool usebp = 0; if (nblkaddr < fn->nblk) { blkaddr = xrealloc(blkaddr, fn->nblk * sizeof *blkaddr); @@ -864,14 +871,24 @@ emitbin(struct function *fn) } memset(blkaddr, 0, nblkaddr * sizeof *blkaddr); - aligncode(pcode, 16); + nops(pcode, 16); start = *pcode; /** prologue **/ - if (fn->stksiz != 0) + + /* only use frame pointer in non-leaf functions and functions that use the stack */ + if (!fn->isleaf || fn->stksiz) { + usebp = 1; /* push rbp; mov rbp, rsp */ DS("\x55\x48\x89\xE5"); - calleesave(pcode, fn); + ++npush; + } + calleesave(&npush, pcode, fn); + + /* ensure stack is 16-byte aligned for function calls */ + if (!fn->isleaf && ((fn->stksiz + npush*8) & 0xF) != 0x8) + fn->stksiz += 8; + if (fn->stksiz != 0) { /* sub rsp, <stack size> */ if (fn->stksiz < 128) @@ -904,7 +921,9 @@ emitbin(struct function *fn) if (blk->jmp.t == Jret) { /* epilogue */ calleerestore(pcode, fn); - if (fn->stksiz) B(0xC9); /* leave */ + if (usebp) B(0xC9); /* leave */ + else if (fn->stksiz) + Xadd(pcode, KPTR, mkoper(OREG, .reg = RSP), mkoper(OIMM, .imm = fn->stksiz)); B(0xC3); /* ret */ } else emitbranch(pcode, blk); } while ((blk = blk->lnext) != fn->entry); @@ -914,7 +933,7 @@ emitbin(struct function *fn) void amd64_emit(struct function *fn) { - fn->stksiz = alignup(fn->stksiz, 16); + fn->stksiz = alignup(fn->stksiz, 8); if (fn->stksiz > 1<<24) error(NULL, "'%s' stack frame too big", fn->name); emitbin(fn); } @@ -144,6 +144,7 @@ struct function { int stksiz; ushort nabiarg, nabiret; bool globl; + bool isleaf; struct bitset regusage[1]; }; @@ -270,6 +270,8 @@ regalloc(struct function *fn) static union ref *stkslotrefsbuf[64]; struct rega ra = {0}; + fn->isleaf = 1; + vinit(&stkslotrefs, stkslotrefsbuf, arraylength(stkslotrefsbuf)); ra.allocs = xcalloc((ninstr*2 < MAXINSTR ? ninstr*2 : MAXINSTR) * sizeof(struct alloc)); ra.nfreegpr = mctarg->ngpr - popcnt(mctarg->rglob->u); @@ -329,6 +331,8 @@ regalloc(struct function *fn) struct call *call = &calltab.p[ins->r.i]; struct bitset rspill[1] = {0}; + fn->isleaf = 0; + for (int r = mctarg->gpr0; r < mctarg->gpr0 + mctarg->ngpr; ++r) if (!bstest(mctarg->rglob, r) && !bstest(mctarg->rcallee, r)) bsset(rspill, r); |