Disable CFI on Mips and add -march to linkflags on ARM.

Mips toolchain does not have ld.gold.
ARM change is a workaround for LLVM r290384.

Bug: 33678192
Test: make ENABLE_CFI=1
Change-Id: I189ffd42760f0ea8d151717337b9355b37cb207b

cc/sanitize.go

@@ -167,7 +167,8 @@ func (sanitize *sanitize) begin(ctx BaseModuleContext) {
 		}
 	}
 
-	if !ctx.AConfig().EnableCFI() {
+	// CFI needs gold linker, and mips toolchain does not have one.
+	if !ctx.AConfig().EnableCFI() || ctx.Arch().ArchType == android.Mips || ctx.Arch().ArchType == android.Mips64 {
 		s.Cfi = nil
 		s.Diag.Cfi = nil
 	}
@@ -312,6 +313,9 @@ func (sanitize *sanitize) flags(ctx ModuleContext, flags Flags) Flags {
 			// __cfi_check needs to be built as Thumb (see the code in linker_cfi.cpp). LLVM is not set up
 			// to do this on a function basis, so force Thumb on the entire module.
 			flags.RequiredInstructionSet = "thumb"
+			// Workaround for b/33678192. CFI jumptables need Thumb2 codegen.  Revert when
+			// Clang is updated past r290384.
+			flags.LdFlags = append(flags.LdFlags, "-march=armv7-a")
 		}
 		sanitizers = append(sanitizers, "cfi")
 		cfiFlags := []string{"-flto", "-fsanitize=cfi", "-fsanitize-cfi-cross-dso"}