Make /fastlink builds as optimized as non-/fastlink builds

build/config/win/BUILD.gn

Index: build/config/win/BUILD.gn
diff --git a/build/config/win/BUILD.gn b/build/config/win/BUILD.gn
index 2b9f7bf77373532e5cca7d033bdd5459d460279f..562c85640d6783a990bd81cd17e2bd88bbdf383d 100644
--- a/build/config/win/BUILD.gn
+++ b/build/config/win/BUILD.gn
@@ -92,9 +92,21 @@ config("compiler") {
   # release image. It is enabled for syzyasan builds and opportunistically for
   # other builds where it is not prohibited (not supported when incrementally
   # linking, using /debug:fastlink, or building with clang).
-  if (is_syzyasan ||
-      (!is_debug && !is_component_build && !is_win_fastlink && !is_clang)) {
-    ldflags = [ "/PROFILE" ]
+  if (is_syzyasan || (!is_debug && !is_component_build && !is_clang)) {
+    if (is_win_fastlink) {

[scottmg, 2016/11/10 21:56:27]

I think this changes the behaviour for is_syzyasan with is_win_fastlink.

I don't think we need to support that combinations, but maybe it would be
clearer to just move the is_syzyasan to a separate if that always sets /PROFILE
and assert(!is_fastlink), and make a second that sets the linker opt flags that
doesn't consider is_syzyasan at all.

[brucedawson, 2016/11/10 22:04:06]

Good catch. Logic is hard. Agreed that it probably doesn't matter but we should
maintain existing logic.

[brucedawson, 2016/11/14 21:34:55]

Done.

+      # /PROFILE implies the following linker flags. Therefore if we are
+      # skipping /PROFILE because it is incompatible with /DEBUG:FASTLINK
+      # we should explicitly add these flags in order to avoid unintended
+      # consequences such as larger binaries.
+      ldflags = [
+        "/OPT:REF",
+        "/OPT:ICF",
+        "/INCREMENTAL:NO",
+        "/FIXED:NO",
+      ]
+    } else {
+      ldflags = [ "/PROFILE" ]
+    }
   }
 
   # arflags apply only to static_libraries. The normal linker configs are only