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authorRuss Cox <rsc@golang.org>2014-05-28 19:50:19 -0400
committerRuss Cox <rsc@golang.org>2014-05-28 19:50:19 -0400
commit73044738e146bec259f7b8e89ecc816a421921aa (patch)
tree181e98d4a3bba678b89ab4f80452cf58daaeed13 /test
parent76fe11c57b2efe4c1ffb53730efadcd928e976c2 (diff)
downloadgo-73044738e146bec259f7b8e89ecc816a421921aa.tar.gz
cmd/gc: fix x=x crash
The 'nodarg' function is used to obtain a Node* representing a function argument or result. It returned a brand new Node*, but that violates the guarantee in most places in the compiler that two Node*s refer to the same variable if and only if they are the same Node* pointer. Reestablish that invariant by making nodarg return a preexisting named variable if present. Having fixed that, avoid any copy during x=x in componentgen, because the VARDEF we emit before the copy marks the lhs x as dead incorrectly. The change in walk.c avoids modifying the result of nodarg. This was the only place in the compiler that did so. Fixes issue 8097. LGTM=r, khr R=golang-codereviews, r, khr CC=golang-codereviews, iant https://codereview.appspot.com/102820043
Diffstat (limited to 'test')
-rw-r--r--test/live.go26
1 files changed, 26 insertions, 0 deletions
diff --git a/test/live.go b/test/live.go
index 21d3e6a5f..286fcc306 100644
--- a/test/live.go
+++ b/test/live.go
@@ -564,3 +564,29 @@ func f38(b bool) {
}
println()
}
+
+// issue 8097: mishandling of x = x during return.
+
+func f39() (x []int) {
+ x = []int{1}
+ println() // ERROR "live at call to printnl: x"
+ return x
+}
+
+func f39a() (x []int) {
+ x = []int{1}
+ println() // ERROR "live at call to printnl: x"
+ return
+}
+
+func f39b() (x [10]*int) {
+ x = [10]*int{new(int)} // ERROR "live at call to new: x"
+ println() // ERROR "live at call to printnl: x"
+ return x
+}
+
+func f39c() (x [10]*int) {
+ x = [10]*int{new(int)} // ERROR "live at call to new: x"
+ println() // ERROR "live at call to printnl: x"
+ return
+}