From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Fri, 3 Mar 2017 17:27:35 +0000 (+0000)
Subject: Remove dead 'copy' commands.
X-Git-Tag: 1.0~39^2~113
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=342379744563365d0d2379a636b6073591814a8a;p=re2c

Remove dead 'copy' commands.

For some reason dead code elimination pass simply ignored 'copy' commands
and removed only dead 'save' commands. Strange as it seems, this went
unnoticed until now (when one of the POSIX tests compiled into C++ code
that triggered GCC warning about use of uninitialized variable).
---

diff --git a/re2c/src/ir/dfa/cfg/dce.cc b/re2c/src/ir/dfa/cfg/dce.cc
index 78bc517f..a19d502e 100644
--- a/re2c/src/ir/dfa/cfg/dce.cc
+++ b/re2c/src/ir/dfa/cfg/dce.cc
@@ -17,6 +17,13 @@ void cfg_t::dead_code_elimination(cfg_t &cfg, const bool *live)
 				ps = &s->next;
 			}
 		}
+		for (tagcopy_t *c, **pc = &b->cmd->copy; (c = *pc);) {
+			if (!live[c->lhs]) {
+				*pc = c->next;
+			} else {
+				pc = &c->next;
+			}
+		}
 	}
 }