Do not use frame pointer by default for MSP430

This is suggested by 3.3.9 of MSP430 EABI document.
We do allow user to manually enable frame pointer. GCC toolchain uses the same behavior.

Patch by Dmitry Mikushev!

Differential Revision: https://reviews.llvm.org/D56925

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@353212 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Driver/ToolChains/Clang.cpp b/lib/Driver/ToolChains/Clang.cpp
index f125bce01ddedfda6619cf34b8e859e4fc91f88e..3b1ef3a5a8695e3c7cb581ab83be6173dbe7eb26 100644 (file)
--- a/lib/Driver/ToolChains/Clang.cpp
+++ b/lib/Driver/ToolChains/Clang.cpp
@@ -519,6 +519,7 @@ static bool useFramePointerForTargetByDefault(const ArgList &Args,
   case llvm::Triple::xcore:
   case llvm::Triple::wasm32:
   case llvm::Triple::wasm64:
+  case llvm::Triple::msp430:
     // XCore never wants frame pointers, regardless of OS.
     // WebAssembly never wants frame pointers.
     return false;

diff --git a/test/CodeGen/msp430-fp-elim.c b/test/CodeGen/msp430-fp-elim.c
new file mode 100644 (file)
index 0000000..c022ade
--- /dev/null
+++ b/test/CodeGen/msp430-fp-elim.c
@@ -0,0 +1,19 @@
+// REQUIRES: msp430-registered-target
+// RUN: %clang_cc1 -mdisable-fp-elim -triple msp430 -S %s -o - | FileCheck %s --check-prefix=FP_ENFORCED
+// RUN: %clang_cc1 -triple msp430 -S %s -o - | FileCheck %s --check-prefix=FP_DEFAULT
+
+// Check the frame pointer is not used on MSP430 by default, but can be forcibly turned on.
+
+// FP_ENFORCED: push r4
+// FP_ENFORCED: mov r4, r4
+// FP_ENFORCED: pop r4
+// FP_DEFAULT: .globl fp_elim_check
+// FP_DEFAULT-NOT: push r4
+// FP_DEFAULT: mov r4, r4
+// FP_DEFAULT-NOT: pop r4
+
+void fp_elim_check()
+{
+       asm volatile ("mov r4, r4");
+}
+