amd64/emit: fix REX-requiring 8-bit GPR encoding checking wrong reg

2 files changed, 4 insertions, 2 deletions

diff --git a/amd64/emit.c b/amd64/emit.c
index 5a63a61..4ad0a04 100644
--- a/amd64/emit.c
+++ b/amd64/emit.c
@@ -293,7 +293,7 @@ encode(uchar **pcode, const struct desc *tab, int ntab, enum irclass k, struct o
       rex |= (dst.reg >> 3) << 2; /* REX.R */
       rex |= (src.reg >> 3) << 0; /* REX.B */
       if (rex) B(0x40 | rex);
-      else if (en->r8 && in_range(dst.reg, RSP, RDI)) {
+      else if (en->r8 && in_range(src.reg, RSP, RDI)) {
          /* /r8 needs REX to encode SP,BP,SI,DI (otherwise -> AH..BH) */
          B(0x40);
       }
@@ -304,7 +304,7 @@ encode(uchar **pcode, const struct desc *tab, int ntab, enum irclass k, struct o
       rex |= (src.reg >> 3) << 2; /* REX.R */
       rex |= (dst.reg >> 3) << 0; /* REX.B */
       if (rex) B(0x40 | rex);
-      else if (en->r8 && in_range(src.reg, RSP, RDI)) {
+      else if (en->r8 && in_range(dst.reg, RSP, RDI)) {
          /* /r8 needs REX to encode SP,BP,SI,DI (otherwise -> AH..BH) */
          B(0x40);
       }
diff --git a/c/c.c b/c/c.c
index 5708419..5a0f5bd 100644
--- a/c/c.c
+++ b/c/c.c
@@ -3227,6 +3227,8 @@ compileexpr(struct function *fn, const struct expr *ex, bool discard)
    case EPLUS:
       r = compileexpr(fn, sub, discard);
       if (discard) return NOREF;
+      if (isscalar(ex->ty) && typesize(ex->ty) < typesize(sub->ty))
+         return narrow(fn, type2cls[scalartypet(ex->ty)], ex->ty, r, 0);
       return cvt(fn, ex->ty, sub->ty, r);
    case ENEG:
       op = Oneg;