Fix building for arm windows with mingw toolchains (#631)

* arm: Check _WIN32 instead of _M_ARM or _MSC_VER for detecting windows

This matches what was done for ARM64 in
c06468fa6674d3783a0edb1d0fae9afc8bc28513.

* arm: Only use armasm source when building with MSVC

When building for windows/arm with clang, the normal gas style .S
source works fine (if fixed up to support thumb and other windows
specifics).

This matches what was done for ARM64 in
c06468fa6674d3783a0edb1d0fae9afc8bc28513.

* arm: Fix sysv.S to work in thumb mode

Align cases in jump tables (adding nop padding to make sure each
case starts where expected).

Rewrite instructions that add directly to the pc register.

For ffi_closure_ret, factor out a call_epilogue subroutine that
restores both sp and pc from the stack; the thumb version of ldm
can't load into the sp register. To avoid excessive ifdeffing, keep
using call_epilogue in arm mode, but keep the shorter "ldm sp, {sp, pc}"
epilogue in that case.

* arm: Add win32 version of trampoline to sysv.S

This matches the version of it in sysv_msvc_arm32.S. The calling
C code expects a specific form of the trampoline on windows; make
sure these work the same on windows regardless of the form of
assembly used.

* arm: Avoid optimizing out clearing the thumb bit of ffi_arm_trampoline

We clear the thumb bit of ffi_arm_trampoline with a bitmask before
memcpying its instructions into closure->tramp.

If the bit isn't cleared, the memcpy of the trampoline function
copies the wrong instructions.

If the ffi_arm_trampoline symbol is declared as an array of int,
the compiler can assume that it is aligned to a 4 byte boundary
and the bitmask operation is a no-op, and optimize it out.

See https://godbolt.org/z/dE3jE1WTz; both Clang and GCC optimize
out the bitmask as it is, while MSVC doesn't. By declaring the
trampoline as an array of unsigned char, the bitmask works as
intended.

diff --git a/configure.host b/configure.host
index 257b7848725c3bbf8a33640124408a2b8837cd61..268267183a031c292a53d3ab11ec475f13c51392 100644 (file)
--- a/configure.host
+++ b/configure.host
@@ -32,7 +32,9 @@ case "${host}" in
 
   arm*-*-cygwin* | arm*-*-mingw* | arm*-*-win* )
        TARGET=ARM_WIN32; TARGETDIR=arm
-       MSVC=1
+       if test "${ax_cv_c_compiler_vendor}" = "microsoft"; then
+         MSVC=1
+       fi
        ;;
 
   arm*-*-*)
@@ -264,7 +266,11 @@ esac
 # ... but some of the cases above share configury.
 case "${TARGET}" in
   ARM_WIN32)
-       SOURCES="ffi.c sysv_msvc_arm32.S"
+       if test "$MSVC" = 1; then
+               SOURCES="ffi.c sysv_msvc_arm32.S"
+       else
+               SOURCES="ffi.c sysv.S"
+       fi
        ;;
   ARM_WIN64)
        if test "$MSVC" = 1; then

diff --git a/src/arm/ffi.c b/src/arm/ffi.c
index b2f60d16aeffd9603405858a2c0a1cd6c95bf465..593ab4d48b8b003f606b1f795284823420656d35 100644 (file)
--- a/src/arm/ffi.c
+++ b/src/arm/ffi.c
@@ -37,7 +37,7 @@
 #include <tramp.h>
 #include "internal.h"
 
-#if defined(_MSC_VER) && defined(_M_ARM)
+#if defined(_WIN32)
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #endif
@@ -49,10 +49,13 @@
 #endif
 
 #else
-#ifndef _M_ARM
+#ifndef _WIN32
 extern unsigned int ffi_arm_trampoline[2] FFI_HIDDEN;
 #else
-extern unsigned int ffi_arm_trampoline[3] FFI_HIDDEN;
+// Declare this as an array of char, instead of array of int,
+// otherwise Clang optimizes out the "& 0xFFFFFFFE" for clearing
+// the thumb bit.
+extern unsigned char ffi_arm_trampoline[12] FFI_HIDDEN;
 #endif
 #endif
 
@@ -104,13 +107,13 @@ ffi_put_arg (ffi_type *ty, void *src, void *dst)
     case FFI_TYPE_SINT32:
     case FFI_TYPE_UINT32:
     case FFI_TYPE_POINTER:
-#ifndef _MSC_VER
+#ifndef _WIN32
     case FFI_TYPE_FLOAT:
 #endif
       *(UINT32 *)dst = *(UINT32 *)src;
       break;
 
-#ifdef _MSC_VER
+#ifdef _WIN32
     // casting a float* to a UINT32* doesn't work on Windows
     case FFI_TYPE_FLOAT:
         *(uintptr_t *)dst = 0;
@@ -633,7 +636,7 @@ ffi_prep_closure_loc (ffi_closure * closure,
 #endif
 
   /* Initialize the dynamic trampoline. */
-#ifndef _M_ARM
+#ifndef _WIN32
   memcpy(closure->tramp, ffi_arm_trampoline, 8);
 #else
   // cast away function type so MSVC doesn't set the lower bit of the function pointer
@@ -643,13 +646,13 @@ ffi_prep_closure_loc (ffi_closure * closure,
 #if defined (__QNX__)
   msync(closure->tramp, 8, 0x1000000); /* clear data map */
   msync(codeloc, 8, 0x1000000);        /* clear insn map */
-#elif defined(_MSC_VER)
+#elif defined(_WIN32)
   FlushInstructionCache(GetCurrentProcess(), closure->tramp, FFI_TRAMPOLINE_SIZE);
 #else
   __clear_cache(closure->tramp, closure->tramp + 8);   /* clear data map */
   __clear_cache(codeloc, codeloc + 8);                 /* clear insn map */
 #endif
-#ifdef _M_ARM
+#ifdef _WIN32
   *(void(**)(void))(closure->tramp + FFI_TRAMPOLINE_CLOSURE_FUNCTION) = closure_func;
 #else
   *(void (**)(void))(closure->tramp + 8) = closure_func;

diff --git a/src/arm/ffitarget.h b/src/arm/ffitarget.h
index cb57b84880ef78fa69898e50b7bb9a6afbaa9507..12d5d206953490121548df9e4f03ed30c03494a9 100644 (file)
--- a/src/arm/ffitarget.h
+++ b/src/arm/ffitarget.h
@@ -43,7 +43,7 @@ typedef enum ffi_abi {
   FFI_SYSV,
   FFI_VFP,
   FFI_LAST_ABI,
-#if defined(__ARM_PCS_VFP) || defined(_M_ARM)
+#if defined(__ARM_PCS_VFP) || defined(_WIN32)
   FFI_DEFAULT_ABI = FFI_VFP,
 #else
   FFI_DEFAULT_ABI = FFI_SYSV,
@@ -57,7 +57,7 @@ typedef enum ffi_abi {
   signed char vfp_args[16]                     \
 
 #define FFI_TARGET_SPECIFIC_VARIADIC
-#ifndef _M_ARM
+#ifndef _WIN32
 #define FFI_TARGET_HAS_COMPLEX_TYPE
 #endif
 
@@ -77,7 +77,7 @@ typedef enum ffi_abi {
 #endif
 
 #else
-#ifdef _MSC_VER
+#ifdef _WIN32
 #define FFI_TRAMPOLINE_SIZE 16
 #define FFI_TRAMPOLINE_CLOSURE_FUNCTION 12
 #else

diff --git a/src/arm/sysv.S b/src/arm/sysv.S
index e816e32d5059007ccd065a15328d5777f953925c..fb36213c6805fa5017154328e094daeaf902a0c5 100644 (file)
--- a/src/arm/sysv.S
+++ b/src/arm/sysv.S
@@ -92,9 +92,25 @@
 #define ARM_FUNC_END(name) \
        SIZE(name)
 
+       .text
+       .syntax unified
+#if defined(_WIN32)
+       /* Windows on ARM is thumb-only */
+       .thumb
+#else
+       /* Keep the assembly in ARM mode in other cases, for simplicity
+        * (to avoid interworking issues). */
+#undef __thumb__
+       .arm
+#endif
+
 /* Aid in defining a jump table with 8 bytes between entries.  */
+#ifdef __thumb__
+/* In thumb mode, instructions can be shorter than expected in arm mode, so
+ * we need to align the start of each case. */
+# define E(index) .align 3
+#elif defined(__clang__)
 /* ??? The clang assembler doesn't handle .if with symbolic expressions.  */
-#ifdef __clang__
 # define E(index)
 #else
 # define E(index)                              \
@@ -103,9 +119,6 @@
        .endif
 #endif
 
-       .text
-       .syntax unified
-       .arm
 
 #ifndef __clang__
        /* We require interworking on LDM, which implies ARMv5T,
@@ -128,6 +141,7 @@ ARM_FUNC_START(ffi_call_VFP)
        cfi_startproc
 
        cmp     r3, #3                  @ load only d0 if possible
+       ite     le
 #ifdef __clang__
        vldrle d0, [r0]
        vldmgt r0, {d0-d7}
@@ -167,9 +181,16 @@ ARM_FUNC_START(ffi_call_SYSV)
        cfi_def_cfa_register(sp)
 
        @ Store values stored in registers.
+#ifndef __thumb__
        .align  3
        add     pc, pc, r3, lsl #3
        nop
+#else
+       adr     ip, 0f
+       add     ip, ip, r3, lsl #3
+       mov     pc, ip
+       .align  3
+#endif
 0:
 E(ARM_TYPE_VFP_S)
 #ifdef __clang__
@@ -228,6 +249,9 @@ ARM_FUNC_END(ffi_go_closure_SYSV)
 ARM_FUNC_START(ffi_closure_SYSV)
        UNWIND(.fnstart)
        cfi_startproc
+#ifdef _WIN32
+       ldmfd   sp!, {r0, ip}                   @ restore fp (r0 is used for stack alignment)
+#endif
        stmdb   sp!, {r0-r3}                    @ save argument regs
        cfi_adjust_cfa_offset(16)
 
@@ -256,7 +280,12 @@ ARM_FUNC_START(ffi_closure_SYSV)
        @ Load values returned in registers.
        add     r2, sp, #8+64                   @ load result
        adr     r3, CNAME(ffi_closure_ret)
+#ifndef __thumb__
        add     pc, r3, r0, lsl #3
+#else
+       add     r3, r3, r0, lsl #3
+       mov     pc, r3
+#endif
        cfi_endproc
        UNWIND(.fnend)
 ARM_FUNC_END(ffi_closure_SYSV)
@@ -275,6 +304,9 @@ ARM_FUNC_END(ffi_go_closure_VFP)
 ARM_FUNC_START(ffi_closure_VFP)
        UNWIND(.fnstart)
        cfi_startproc
+#ifdef _WIN32
+       ldmfd   sp!, {r0, ip}                   @ restore fp (r0 is used for stack alignment)
+#endif
        stmdb   sp!, {r0-r3}                    @ save argument regs
        cfi_adjust_cfa_offset(16)
 
@@ -306,7 +338,12 @@ ARM_FUNC_START(ffi_closure_VFP)
        @ Load values returned in registers.
        add     r2, sp, #8+64                   @ load result
        adr     r3, CNAME(ffi_closure_ret)
+#ifndef __thumb__
        add     pc, r3, r0, lsl #3
+#else
+       add     r3, r3, r0, lsl #3
+       mov     pc, r3
+#endif
        cfi_endproc
        UNWIND(.fnend)
 ARM_FUNC_END(ffi_closure_VFP)
@@ -326,32 +363,40 @@ E(ARM_TYPE_VFP_S)
 #else
        ldc     p10, cr0, [r2]                  @ vldr s0, [r2]
 #endif
-       ldm     sp, {sp,pc}
+       b       call_epilogue
 E(ARM_TYPE_VFP_D)
 #ifdef __clang__
        vldr d0, [r2]
 #else
        ldc     p11, cr0, [r2]                  @ vldr d0, [r2]
 #endif
-       ldm     sp, {sp,pc}
+       b       call_epilogue
 E(ARM_TYPE_VFP_N)
 #ifdef __clang__
        vldm r2, {d0-d3}
 #else
        ldc     p11, cr0, [r2], {8}             @ vldm r2, {d0-d3}
 #endif
-       ldm     sp, {sp,pc}
+       b       call_epilogue
 E(ARM_TYPE_INT64)
        ldr     r1, [r2, #4]
        nop
 E(ARM_TYPE_INT)
        ldr     r0, [r2]
-       ldm     sp, {sp,pc}
+       b       call_epilogue
 E(ARM_TYPE_VOID)
-       ldm     sp, {sp,pc}
+       b       call_epilogue
        nop
 E(ARM_TYPE_STRUCT)
+       b       call_epilogue
+call_epilogue:
+#ifndef __thumb__
        ldm     sp, {sp,pc}
+#else
+       ldm     sp, {ip,lr}
+       mov     sp, ip
+       bx      lr
+#endif
        cfi_endproc
 ARM_FUNC_END(ffi_closure_ret)
 
@@ -419,6 +464,15 @@ ARM_FUNC_START(ffi_closure_trampoline_table_page)
 ARM_FUNC_END(ffi_closure_trampoline_table_page)
 #endif
 
+#elif defined(_WIN32)
+
+ARM_FUNC_START(ffi_arm_trampoline)
+0:     adr     ip, 0b
+       stmdb   sp!, {r0, ip}
+       ldr     pc, 1f
+1:     .long   0
+ARM_FUNC_END(ffi_arm_trampoline)
+
 #else
 
 ARM_FUNC_START(ffi_arm_trampoline)