From 9632f2f148bf545fea09f25f34a316ec8ae86256 Mon Sep 17 00:00:00 2001
From: Quentin Carbonneaux <quentin@c9x.me>
Date: Sat, 11 Mar 2023 21:51:10 +0100
Subject: kill dead stores when coalescing slots

This is necessary because, post
fusion, dead stores may clobber
data.  A new test case exposes
one such situation.
---
 test/mem2.ssa | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 test/mem2.ssa

(limited to 'test')

diff --git a/test/mem2.ssa b/test/mem2.ssa
new file mode 100644
index 0000000..4a136b4
--- /dev/null
+++ b/test/mem2.ssa
@@ -0,0 +1,32 @@
+# Ember Sawady reported this bug
+# in stack-slot coalescing
+
+type :t = { w 2 }
+
+function :t $func() {
+@start.0
+	%temp =l alloc4 4
+	%ret =l alloc4 8
+	storew 1, %temp
+	# storew can also go here
+	%field =l add %ret, 4
+	storew 2, %ret
+	blit %temp, %field, 4
+	# removing either of these storews causes it to work
+	storew 2, %ret
+	ret %ret
+}
+
+export function w $main() {
+@start
+	%ret =:t call $func()
+	%fptr =l add %ret, 4
+	%field =w loaduw %fptr
+	%x =w ceqw %field, 1
+	jnz %x, @passed, @failed
+@failed
+	# this fails despite 1 => temp => ret + 4 => field
+	call $abort()
+@passed
+	ret 0
+}
-- 
cgit 1.4.1