Fix Phi elimination pass sometimes leaving broken insts in release builds (#7499)

* Make phi elimination pass modify branches in-place

* Add test and fix formatting

* Avoid double removal of param insts

1 files changed, 5 insertions, 0 deletions

diff --git a/tests/bugs/gh-7499.slang.expected b/tests/bugs/gh-7499.slang.expected
new file mode 100644
index 000000000..4c32e2510
--- /dev/null
+++ b/tests/bugs/gh-7499.slang.expected
@@ -0,0 +1,5 @@
+result code = 0
+standard error = {
+}
+standard output = {
+}