Initial version of a go version of the compiler wrapper.

Still calls the old wrapper if one of the following flags is given:
- Xclang-path
- clang-syntax
- env WITH_TIDY
- env FORCE_DISABLE_WERROR
- env GETRUSAGE
- env BISECT_STAGE

BUG=chromium:773875
TEST=Unit tests that also verify the produced command against the
TEST=existing compiler wrapper.

Change-Id: I1e0a720ce9f485d8015deefb2682f2cb760d82e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/1652057
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Tobias Bosch <tbosch@google.com>
Reviewed-by: George Burgess <gbiv@chromium.org>
Tested-by: Tobias Bosch <tbosch@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/compiler_wrapper/thumb_flags.go b/compiler_wrapper/thumb_flags.go
new file mode 100644
index 00000000..fa65875e
--- /dev/null
+++ b/compiler_wrapper/thumb_flags.go
@@ -0,0 +1,23 @@
+package main
+
+import (
+	"strings"
+)
+
+func processThumbCodeFlags(builder *commandBuilder) {
+	arch := builder.target.arch
+	if builder.target.abi != "eabi" && (strings.HasPrefix(arch, "armv7") || strings.HasPrefix(arch, "armv8")) {
+		// ARM32 specfic:
+		// 1. Generate thumb codes by default.  GCC is configured with
+		//    --with-mode=thumb and defaults to thumb mode already.  This
+		//    changes the default behavior of clang and doesn't affect GCC.
+		// 2. Do not force frame pointers on ARM32 (https://crbug.com/693137).
+		builder.addPreUserArgs("-mthumb")
+		builder.transformArgs(func(arg builderArg) string {
+			if !arg.FromUser && arg.Value == "-fno-omit-frame-pointer" {
+				return ""
+			}
+			return arg.Value
+		})
+	}
+}