From 82f5ba58cf76bc431afe0c738cdcfe1f5998ae95 Mon Sep 17 00:00:00 2001
From: Quentin Carbonneaux <quentin@c9x.me>
Date: Fri, 26 Apr 2019 12:05:47 +0200
Subject: restore some code from b4a98c

I had forgotten that %rip can only be
used as base when there is no index.

I also added a test which stresses
addressing selection with and without
constants.
---
 amd64/isel.c     | 18 +++++++++++++++-
 test/conaddr.ssa | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 test/conaddr.ssa

diff --git a/amd64/isel.c b/amd64/isel.c
index ce0c98f..e5202cb 100644
--- a/amd64/isel.c
+++ b/amd64/isel.c
@@ -62,7 +62,7 @@ static void
 fixarg(Ref *r, int k, int op, Fn *fn)
 {
 	char buf[32];
-	Addr a;
+	Addr a, *m;
 	Ref r0, r1;
 	int s, n, cpy, mem;
 
@@ -110,6 +110,22 @@ fixarg(Ref *r, int k, int op, Fn *fn)
 		r1 = newtmp("isel", Kl, fn);
 		emit(Oaddr, Kl, r1, r0, R);
 	}
+	else if (rtype(r0) == RMem) {
+		/* eliminate memory operands of
+		 * the form $foo(%rip, ...)
+		 */
+		m = &fn->mem[r0.val];
+		if (req(m->base, R))
+		if (m->offset.type == CAddr) {
+			n = fn->ncon;
+			vgrow(&fn->con, ++fn->ncon);
+			fn->con[n] = m->offset;
+			m->offset.type = CUndef;
+			r0 = newtmp("isel", Kl, fn);
+			emit(Oaddr, Kl, r0, CON(n), R);
+			m->base = r0;
+		}
+	}
 	*r = r1;
 }
 
diff --git a/test/conaddr.ssa b/test/conaddr.ssa
new file mode 100644
index 0000000..3f0aba7
--- /dev/null
+++ b/test/conaddr.ssa
@@ -0,0 +1,65 @@
+# test amd64 addressing modes
+
+export
+function w $f0(l %o) {
+@start
+	%addr =l add $a, %o
+	%char =w loadub %addr
+	ret %char
+}
+
+export
+function w $f1(l %o) {
+@start
+	%o1 =l mul %o, 1
+	%addr =l add 10, %o1
+	%char =w loadub %addr
+	ret %char
+}
+
+export
+function w $f2(l %o1, l %o2) {
+@start
+	%o22 =l mul %o2, 2
+	%o =l add %o1, %o22
+	%addr =l add $a, %o
+	%char =w loadub %addr
+	ret %char
+}
+
+export
+function l $f3(l %o) {
+@start
+	%addr =l add %o, $a
+	ret %addr
+}
+
+export
+function $writeto0() {
+@start
+	storel 0, 0
+	ret
+}
+
+# >>> driver
+# #include <stdlib.h>
+# #include <signal.h>
+# char a[] = "qbe rocks";
+# int ok = 1;
+# extern unsigned f0(long), f1(long), f2(long, long);
+# extern char *f3(long);
+# extern void writeto0();
+# void h(int sig, siginfo_t *si, void *unused) {
+# 	ok &= si->si_addr == 0;
+# 	exit(!ok);
+# }
+# int main() {
+# 	struct sigaction sa = {.sa_flags=SA_SIGINFO, .sa_sigaction=h};
+# 	sigemptyset(&sa.sa_mask); sigaction(SIGSEGV, &sa, 0);
+# 	ok &= f0(2) == 'e';
+# 	ok &= f1((long)a-5) == 'o';
+# 	ok &= f2(4, 2) == 's';
+# 	ok &= *f3(0) == 'q';
+# 	writeto0(); /* will segfault */
+# }
+# <<<
-- 
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