From ce0ab53ed73fb24f9537cab762467efad56f2664 Mon Sep 17 00:00:00 2001
From: Quentin Carbonneaux <quentin@c9x.me>
Date: Wed, 6 Feb 2019 08:34:51 +0100
Subject: 2 bug fixes in rega

The worst one was that "part 3" of rega()
could break the critical invariant that
two interferring temporaries get assigned
different registers.  This is fixed by
being careful when changing the register
of a temporary based on predecessor
blocks.

Thanks to Michael Forney for reporting
these bugs and helping with the analysis.
---
 test/rega1.ssa | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 test/rega1.ssa

(limited to 'test/rega1.ssa')

diff --git a/test/rega1.ssa b/test/rega1.ssa
new file mode 100644
index 0000000..9e87c89
--- /dev/null
+++ b/test/rega1.ssa
@@ -0,0 +1,24 @@
+# tests that %b and %a0 do not end up in
+# the same register at the start of @loop
+
+export function l $f(l %a) {
+@start
+@loop
+	%b =l phi @start 42, @loop0 %a1, @loop1 %a1
+	%a0 =l phi @start %a, @loop0 %a1, @loop1 %a1
+	%a1 =l sub %a0, 1
+	jnz %b, @loop0, @loop1
+@loop0
+	jnz %a1, @loop, @end
+@loop1
+	jnz %a1, @loop, @end
+@end
+	ret %b
+}
+
+# >>> driver
+# extern long long f(long long);
+# int main() {
+# 	return !(f(1) == 42 && f(2) == 1 && f(42) == 1);
+# }
+# <<<
-- 
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