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| author | Russ Cox <rsc@golang.org> | 2010-10-07 04:42:26 -0400 |
|---|---|---|
| committer | Russ Cox <rsc@golang.org> | 2010-10-07 04:42:26 -0400 |
| commit | 9ba0bfc17c1c812a86fe912e19d005baa9eed9a3 (patch) | |
| tree | f82d8d09026b3dbbe1f1f6b5beb12715674a24eb /src/cmd/gc/gen.c | |
| parent | 02647460c22c62b6def1bba1e29036ab20eca00d (diff) | |
| download | go-9ba0bfc17c1c812a86fe912e19d005baa9eed9a3.tar.gz | |
gc: elide dead code
R=ken2
CC=golang-dev
http://codereview.appspot.com/2365044
Diffstat (limited to 'src/cmd/gc/gen.c')
| -rw-r--r-- | src/cmd/gc/gen.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/cmd/gc/gen.c b/src/cmd/gc/gen.c index d2396aa09..a8b2e1b8e 100644 --- a/src/cmd/gc/gen.c +++ b/src/cmd/gc/gen.c @@ -257,6 +257,17 @@ gen(Node *n) break; case OIF: + if(n->ntest == N || n->ntest->op == OLITERAL) { + // drop dead code in if true or if false. + // the linker will do it for us in general, + // but this avoids writnig to the object file + // in a very common case. + if(n->ntest == N || n->ntest->val.u.bval) + genlist(n->nbody); + else + genlist(n->nelse); + break; + } p1 = gjmp(P); // goto test p2 = gjmp(P); // p2: goto else patch(p1, pc); // test: |