From 487079af3d6f39b379f52f7e0ea6edec63587e5b Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Sat, 27 Apr 2024 14:29:02 -0700
Subject: qbe: Add extra size for strict alignment with QBE instruction

With upcoming VLA support, the size might not be constant.
---
 qbe.c                         |  7 +++----
 test/alignas-local-32.c       |  4 ----
 test/alignas-local-32.qbe     | 11 -----------
 test/alignas-local-strict.c   |  4 ++++
 test/alignas-local-strict.qbe | 12 ++++++++++++
 5 files changed, 19 insertions(+), 19 deletions(-)
 delete mode 100644 test/alignas-local-32.c
 delete mode 100644 test/alignas-local-32.qbe
 create mode 100644 test/alignas-local-strict.c
 create mode 100644 test/alignas-local-strict.qbe

diff --git a/qbe.c b/qbe.c
index adbc6f7..c3424c5 100644
--- a/qbe.c
+++ b/qbe.c
@@ -268,24 +268,23 @@ funcalloc(struct func *f, struct decl *d)
 	enum instkind op;
 	struct block *end;
 	struct value *v;
-	unsigned long long size;
 	int align;
 
 	assert(!d->type->incomplete);
 	assert(d->type->size > 0);
 	end = f->end;
 	f->end = f->start;
-	size = d->type->size;
+	v = mkintconst(d->type->size);
 	align = d->u.obj.align;
 	switch (align) {
 	case 1:
 	case 2:
 	case 4:  op = IALLOC4; break;
 	case 8:  op = IALLOC8; break;
-	default: size += align - 16; /* fallthrough */
+	default: v = funcinst(f, IADD, ptrclass, v, mkintconst(align - 16));  /* fallthrough */
 	case 16: op = IALLOC16; break;
 	}
-	v = funcinst(f, op, ptrclass, mkintconst(size), NULL);
+	v = funcinst(f, op, ptrclass, v, NULL);
 	if (align > 16) {
 		/* TODO: implement alloc32 in QBE and use that instead */
 		v = funcinst(f, IADD, ptrclass, v, mkintconst(align - 16));
diff --git a/test/alignas-local-32.c b/test/alignas-local-32.c
deleted file mode 100644
index e390713..0000000
--- a/test/alignas-local-32.c
+++ /dev/null
@@ -1,4 +0,0 @@
-int main(void) {
-	alignas(32) char x;
-	return (unsigned long)&x % 32;
-}
diff --git a/test/alignas-local-32.qbe b/test/alignas-local-32.qbe
deleted file mode 100644
index 53bfab3..0000000
--- a/test/alignas-local-32.qbe
+++ /dev/null
@@ -1,11 +0,0 @@
-export
-function w $main() {
-@start.1
-	%.1 =l alloc16 17
-	%.2 =l add %.1, 16
-	%.3 =l and %.2, 18446744073709551584
-@body.2
-	%.4 =l extsw 32
-	%.5 =l urem %.3, %.4
-	ret %.5
-}
diff --git a/test/alignas-local-strict.c b/test/alignas-local-strict.c
new file mode 100644
index 0000000..e390713
--- /dev/null
+++ b/test/alignas-local-strict.c
@@ -0,0 +1,4 @@
+int main(void) {
+	alignas(32) char x;
+	return (unsigned long)&x % 32;
+}
diff --git a/test/alignas-local-strict.qbe b/test/alignas-local-strict.qbe
new file mode 100644
index 0000000..8c725ff
--- /dev/null
+++ b/test/alignas-local-strict.qbe
@@ -0,0 +1,12 @@
+export
+function w $main() {
+@start.1
+	%.1 =l add 1, 16
+	%.2 =l alloc16 %.1
+	%.3 =l add %.2, 16
+	%.4 =l and %.3, 18446744073709551584
+@body.2
+	%.5 =l extsw 32
+	%.6 =l urem %.4, %.5
+	ret %.6
+}
-- 
cgit v1.2.3