From 6b5d015ee3ad1fe46e3238b7505dd6e0047a8f7b Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Wed, 7 Apr 2021 16:48:22 -0700
Subject: qbe: Remove unnecessary extension for relational operands

The operands are already promoted, so never need to be extended.

These extend()s were added in 7d746860 in an attempt to fix a bug
related to the comparison of values with type smaller than int.
However, the real bug was that the operands should have been promoted
to int by usual arithmetic conversions, which was fixed later in
a8131372.
---
 qbe.c | 35 +++++++----------------------------
 1 file changed, 7 insertions(+), 28 deletions(-)

diff --git a/qbe.c b/qbe.c
index f3a6f44..2fdcc9c 100644
--- a/qbe.c
+++ b/qbe.c
@@ -450,19 +450,6 @@ ftou(struct func *f, struct repr *r, struct value *v)
 	return &join->phi.res;
 }
 
-static struct value *
-extend(struct func *f, struct type *t, struct value *v)
-{
-	enum instkind op;
-
-	switch (t->size) {
-	case 1: op = t->basic.issigned ? IEXTSB : IEXTUB; break;
-	case 2: op = t->basic.issigned ? IEXTSH : IEXTUH; break;
-	default: return v;
-	}
-	return funcinst(f, op, &i32, v, NULL);
-}
-
 static struct value *
 convert(struct func *f, struct type *dst, struct type *src, struct value *l)
 {
@@ -478,12 +465,16 @@ convert(struct func *f, struct type *dst, struct type *src, struct value *l)
 	if (!(src->prop & PROPREAL) || !(dst->prop & PROPREAL))
 		fatal("internal error; unsupported conversion");
 	if (dst->kind == TYPEBOOL) {
-		l = extend(f, src, l);
 		r = mkintconst(src->repr, 0);
-		if (src->prop & PROPINT)
+		if (src->prop & PROPINT) {
+			switch (src->size) {
+			case 1: l = funcinst(f, IEXTUB, &i32, l, NULL); break;
+			case 2: l = funcinst(f, IEXTUH, &i32, l, NULL); break;
+			}
 			op = src->size == 8 ? ICNEL : ICNEW;
-		else
+		} else {
 			op = src->size == 8 ? ICNED : ICNES;
+		}
 	} else if (dst->prop & PROPINT) {
 		if (src->prop & PROPINT) {
 			if (dst->size <= src->size) {
@@ -823,48 +814,36 @@ funcexpr(struct func *f, struct expr *e)
 			op = IXOR;
 			break;
 		case TLESS:
-			l = extend(f, t, l);
-			r = extend(f, t, r);
 			if (t->size <= 4)
 				op = t->prop & PROPFLOAT ? ICLTS : t->basic.issigned ? ICSLTW : ICULTW;
 			else
 				op = t->prop & PROPFLOAT ? ICLTD : t->basic.issigned ? ICSLTL : ICULTL;
 			break;
 		case TGREATER:
-			l = extend(f, t, l);
-			r = extend(f, t, r);
 			if (t->size <= 4)
 				op = t->prop & PROPFLOAT ? ICGTS : t->basic.issigned ? ICSGTW : ICUGTW;
 			else
 				op = t->prop & PROPFLOAT ? ICGTD : t->basic.issigned ? ICSGTL : ICUGTL;
 			break;
 		case TLEQ:
-			l = extend(f, t, l);
-			r = extend(f, t, r);
 			if (t->size <= 4)
 				op = t->prop & PROPFLOAT ? ICLES : t->basic.issigned ? ICSLEW : ICULEW;
 			else
 				op = t->prop & PROPFLOAT ? ICLED : t->basic.issigned ? ICSLEL : ICULEL;
 			break;
 		case TGEQ:
-			l = extend(f, t, l);
-			r = extend(f, t, r);
 			if (t->size <= 4)
 				op = t->prop & PROPFLOAT ? ICGES : t->basic.issigned ? ICSGEW : ICUGEW;
 			else
 				op = t->prop & PROPFLOAT ? ICGED : t->basic.issigned ? ICSGEL : ICUGEL;
 			break;
 		case TEQL:
-			l = extend(f, t, l);
-			r = extend(f, t, r);
 			if (t->size <= 4)
 				op = t->prop & PROPFLOAT ? ICEQS : ICEQW;
 			else
 				op = t->prop & PROPFLOAT ? ICEQD : ICEQL;
 			break;
 		case TNEQ:
-			l = extend(f, t, l);
-			r = extend(f, t, r);
 			if (t->size <= 4)
 				op = t->prop & PROPFLOAT ? ICNES : ICNEW;
 			else
-- 
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