clang-format files to ensure styles differ under compiler/.

PiperOrigin-RevId: 270137577
diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..d37983a
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,3 @@
+# All of IREE is in the Google style except for iree/compiler/, which follows
+# the LLVM style (along with MLIR).
+BasedOnStyle: Google
diff --git a/iree/compiler/.clang-format b/iree/compiler/.clang-format
new file mode 100644
index 0000000..a74fda4
--- /dev/null
+++ b/iree/compiler/.clang-format
@@ -0,0 +1,2 @@
+BasedOnStyle: LLVM
+AlwaysBreakTemplateDeclarations: Yes