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cgen: f64 deref-load -> MOVSD/MOVSS into X0 (both stages, #96)

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Hojun-Cho
2026-05-25 12:27:19 +09:00
parent 0d1ae17dd0
commit 2f2a73bd41
4 changed files with 52 additions and 4 deletions
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9
cmd/w6c/cgen.c
View File

@@ -2284,7 +2284,16 @@ cgexpr(Cg *c, Node *n, Local *locals)
/* Handled in the pre-cgexpr early-exit above. */ /* Handled in the pre-cgexpr early-exit above. */
break; break;
case TK_STAR: /* deref */ case TK_STAR: /* deref */
/* f64/f32 result rides X0 (SSE), not AX — an integer
* MOVQ strands the value off the float ABI and the
* caller's MOVSD X0 reads stale bits (#96). Mirrors the
* float field/ident load idiom at 1462/1838. */
if (node_isfloat(n)) {
ins2(c, node_isf32(n) ? A_MOVSS : A_MOVSD,
amem(D_AX, 0), areg(D_X0));
} else {
ins2(c, A_MOVQ, amem(D_AX, 0), areg(D_AX)); ins2(c, A_MOVQ, amem(D_AX, 0), areg(D_AX));
}
break; break;
default: break; default: break;
} }

15
selfhost/cmd/w6c/main.combined.ww
View File

@@ -16759,7 +16759,20 @@ fn cgun(c: *cgen, n: *node) void = {
}; };
return; return;
}; };
if (n.op == tkind.TK_STAR) { emitline("\tMOVQ\t(AX), AX\n"); return; }; if (n.op == tkind.TK_STAR) {
// f64/f32 result rides X0 (SSE), not AX — an integer MOVQ
// strands the value off the float ABI and the caller's
// MOVSD X0 reads stale bits (#96). Mirrors the float
// field/ident load idiom.
if (isfloattype(c, n)) {
let mov: str = "MOVSD";
if (isf32type(c, n)) { mov = "MOVSS"; };
emitline("\t"); emitline(mov); emitline("\t(AX), X0\n");
} else {
emitline("\tMOVQ\t(AX), AX\n");
};
return;
};
if (n.op == tkind.TK_NOT) { if (n.op == tkind.TK_NOT) {
let t: str = mklabel(c, "tt"); let t: str = mklabel(c, "tt");
let e: str = mklabel(c, "te"); let e: str = mklabel(c, "te");

15
selfhost/cmd/wcc/cgenexpr.ww
View File

@@ -2736,7 +2736,20 @@ fn cgun(c: *cgen, n: *node) void = {
}; };
return; return;
}; };
if (n.op == tkind.TK_STAR) { emitline("\tMOVQ\t(AX), AX\n"); return; }; if (n.op == tkind.TK_STAR) {
// f64/f32 result rides X0 (SSE), not AX — an integer MOVQ
// strands the value off the float ABI and the caller's
// MOVSD X0 reads stale bits (#96). Mirrors the float
// field/ident load idiom.
if (isfloattype(c, n)) {
let mov: str = "MOVSD";
if (isf32type(c, n)) { mov = "MOVSS"; };
emitline("\t"); emitline(mov); emitline("\t(AX), X0\n");
} else {
emitline("\tMOVQ\t(AX), AX\n");
};
return;
};
if (n.op == tkind.TK_NOT) { if (n.op == tkind.TK_NOT) {
let t: str = mklabel(c, "tt"); let t: str = mklabel(c, "tt");
let e: str = mklabel(c, "te"); let e: str = mklabel(c, "te");

15
selfhost/cmd/wwdump/main.combined.ww
View File

@@ -16759,7 +16759,20 @@ fn cgun(c: *cgen, n: *node) void = {
}; };
return; return;
}; };
if (n.op == tkind.TK_STAR) { emitline("\tMOVQ\t(AX), AX\n"); return; }; if (n.op == tkind.TK_STAR) {
// f64/f32 result rides X0 (SSE), not AX — an integer MOVQ
// strands the value off the float ABI and the caller's
// MOVSD X0 reads stale bits (#96). Mirrors the float
// field/ident load idiom.
if (isfloattype(c, n)) {
let mov: str = "MOVSD";
if (isf32type(c, n)) { mov = "MOVSS"; };
emitline("\t"); emitline(mov); emitline("\t(AX), X0\n");
} else {
emitline("\tMOVQ\t(AX), AX\n");
};
return;
};
if (n.op == tkind.TK_NOT) { if (n.op == tkind.TK_NOT) {
let t: str = mklabel(c, "tt"); let t: str = mklabel(c, "tt");
let e: str = mklabel(c, "te"); let e: str = mklabel(c, "te");