[X86] Support 'interrupt' attribute for x86

This attribute may be attached to a function definition and instructs the backend to generate appropriate function entry/exit code so that
it can be used directly as an interrupt handler.
The IRET instruction, instead of the RET instruction, is used to return from interrupt or exception handlers. All registers, except for the EFLAGS register which is restored by the IRET instruction, are preserved by the compiler.
Any interruptible-without-stack-switch code must be compiled with -mno-red-zone since interrupt handlers can and will, because of the hardware design, touch
the red zone.

interrupt handler must be declared with a mandatory pointer argument:
struct interrupt_frame;

__attribute__ ((interrupt))
void f (struct interrupt_frame *frame) {
    ...
}
and user must properly define the structure the pointer pointing to.

exception handler: 

The exception handler is very similar to the interrupt handler with a different mandatory function signature:
#ifdef __x86_64__
typedef unsigned long long int uword_t;
#else
typedef unsigned int uword_t;
#endif

struct interrupt_frame;

__attribute__ ((interrupt))
void f (struct interrupt_frame *frame, uword_t error_code) {
    ...
}
and compiler pops the error code off stack before the IRET instruction.

The exception handler should only be used for exceptions which push an error code and all other exceptions must use the interrupt handler.
The system will crash if the wrong handler is used.
Differential Revision: http://reviews.llvm.org/D15709

llvm-svn: 257867

1 files changed, 35 insertions, 0 deletions

diff --git a/clang/test/CodeGenCXX/attr-x86-interrupt.cpp b/clang/test/CodeGenCXX/attr-x86-interrupt.cpp
new file mode 100644
index 00000000000..50001046903
--- /dev/null
+++ b/clang/test/CodeGenCXX/attr-x86-interrupt.cpp
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -o - | FileCheck %s --check-prefix=X86_64_LINUX
+// RUN: %clang_cc1 -triple i386-unknown-linux-gnu %s -emit-llvm -o - | FileCheck %s --check-prefix=X86_LINUX
+// RUN: %clang_cc1 -triple x86_64-pc-win32 %s -emit-llvm -o - | FileCheck %s --check-prefix=X86_64_WIN
+// RUN: %clang_cc1 -triple i386-pc-win32 %s -emit-llvm -o - | FileCheck %s --check-prefix=X86_WIN
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnux32 %s -emit-llvm -o - | FileCheck %s --check-prefix=X86_64_LINUX
+
+#ifdef __x86_64__
+typedef __UINT64_TYPE__ uword;
+#else
+typedef __UINT32_TYPE__ uword;
+#endif
+
+__attribute__((interrupt)) void foo7(int *a, uword b) {}
+namespace S {
+__attribute__((interrupt)) void foo8(int *a) {}
+}
+struct St {
+static void foo9(int *a) __attribute__((interrupt)) {}
+};
+// X86_64_LINUX: @llvm.used = appending global [3 x i8*] [i8* bitcast (void (i32*, i64)* @{{.*}}foo7{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo8{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo9{{.*}} to i8*)], section "llvm.metadata"
+// X86_64_LINUX: define x86_intrcc void @{{.*}}foo7{{.*}}(i32* %{{.+}}, i64 %{{.+}})
+// X86_64_LINUX: define x86_intrcc void @{{.*}}foo8{{.*}}(i32* %{{.+}})
+// X86_64_LINUX: define linkonce_odr x86_intrcc void @{{.*}}foo9{{.*}}(i32* %{{.+}})
+// X86_LINUX: @llvm.used = appending global [3 x i8*] [i8* bitcast (void (i32*, i32)* @{{.*}}foo7{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo8{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo9{{.*}} to i8*)], section "llvm.metadata"
+// X86_LINUX: define x86_intrcc void @{{.*}}foo7{{.*}}(i32* %{{.+}}, i32 %{{.+}})
+// X86_LINUX: define x86_intrcc void @{{.*}}foo8{{.*}}(i32* %{{.+}})
+// X86_LINUX: define linkonce_odr x86_intrcc void @{{.*}}foo9{{.*}}(i32* %{{.+}})
+// X86_64_WIN: @llvm.used = appending global [3 x i8*] [i8* bitcast (void (i32*, i64)* @{{.*}}foo7{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo8{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo9{{.*}} to i8*)], section "llvm.metadata"
+// X86_64_WIN: define x86_intrcc void @{{.*}}foo7{{.*}}(i32* %{{.+}}, i64 %{{.+}})
+// X86_64_WIN: define x86_intrcc void @{{.*}}foo8{{.*}}(i32* %{{.+}})
+// X86_64_WIN: define linkonce_odr x86_intrcc void @{{.*}}foo9{{.*}}(i32* %{{.+}})
+// X86_WIN: @llvm.used = appending global [3 x i8*] [i8* bitcast (void (i32*, i32)* @{{.*}}foo7{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo8{{.*}} to i8*), i8* bitcast (void (i32*)* @{{.*}}foo9{{.*}} to i8*)], section "llvm.metadata"
+// X86_WIN: define x86_intrcc void @{{.*}}foo7{{.*}}(i32* %{{.+}}, i32 %{{.+}})
+// X86_WIN: define x86_intrcc void @{{.*}}foo8{{.*}}(i32* %{{.+}})
+// X86_WIN: define linkonce_odr x86_intrcc void @{{.*}}foo9{{.*}}(i32* %{{.+}})