[libc] Add fenv_t and signal macros in riscv

[mikhail.ramalho]

Summary

This patch now enables full build.

[sivachandra]

libc/config/linux/app.h

40

Do we need this change for full build?

[abrachet]

libc/include/llvm-libc-types/fenv_t.h

27

I think the __riscv check should be above this

[mikhail.ramalho]

libc/config/linux/app.h

40

I'll double-check

[mikhail.ramalho]

• Removed unnecessary define from app.h (for full build)
• Fix riscv define in the wrong place in fenv_t.h

[mcgrathr]

libc/include/llvm-libc-types/fenv_t.h

27

I would *highly* recommend never using a typedef to a base type (or other existing type) like this. It's much better to define a struct with a single member, as you can see done for the ARM case above. This ensures that the API contract enforces that fenv_t and fenv_t* values are passed, rather than unsigned int or unsigned int*. On x86-64, ARM, and RISC-V, the calling convention for a struct like this is the same as for the bare integer type.

libc/config/linux/app.h

struct TLSImage {
   // PT_TLS header.
   uintptr_t init_size;
 
   // The alignment of the TLS layout. It assumed that the alignment
   // value is a power of 2.
   uintptr_t align;
 };
 
-#if defined(LIBC_TARGET_ARCH_IS_X86_64) || defined(LIBC_TARGET_ARCH_IS_AARCH64)
+#if defined(LIBC_TARGET_ARCH_IS_X86_64) ||                                     \
+    defined(LIBC_TARGET_ARCH_IS_AARCH64) ||                                    \
+    defined(LIBC_TARGET_ARCH_IS_RISCV64)
 // At the language level, argc is an int. But we use uint64_t as the x86_64
 // ABI specifies it as an 8 byte value. Likewise, in the ARM64 ABI, arguments
 // are usually passed in registers.  x0 is a doubleword register, so this is
 // 64 bit for aarch64 as well.
 typedef uint64_t ArgcType;
 
 // At the language level, argv is a char** value. However, we use uint64_t as
 // ABIs specify the argv vector be an |argc| long array of 8-byte values.

libc/include/llvm-libc-macros/linux/signal-macros.h

 #define SS_DISABLE 0x2
 
 #ifdef __x86_64__
 #define MINSIGSTKSZ 2048
 #define SIGSTKSZ 8192
 #elif defined(__aarch64__)
 #define MINSIGSTKSZ 5120
 #define SIGSTKSZ 16384
+#elif defined(__riscv)
+#define MINSIGSTKSZ 2048
+#define SIGSTKSZ 8192
 #else
 #error "Signal stack sizes not defined for your platform."
 #endif
 
 #define SIG_DFL ((__sighandler_t)0)
 #define SIG_IGN ((__sighandler_t)1)
 #define SIG_ERR ((__sighandler_t)-1)
 
 #endif // __LLVM_LIBC_MACROS_LINUX_SIGNUM_MACROS_H

libc/include/llvm-libc-types/fenv_t.h

typedef struct {
   unsigned char __x86_status[28];
   unsigned char __mxcsr[4];
 } fenv_t;
 #elif defined(__arm__) || defined(_M_ARM)
 typedef struct {
   unsigned int __fpscr;
 } fenv_t;
 #else
 #error "fenv_t not defined for your platform"
 #endif
+#ifdef __riscv
+typedef unsigned int fenv_t;
+#endif
 
 #endif // __LLVM_LIBC_TYPES_FENV_T_H__

libc/src/__support/FPUtil/FEnvImpl.h

 LIBC_INLINE int clear_except(int) { return 0; }
 
 LIBC_INLINE int test_except(int) { return 0; }
 
 LIBC_INLINE int set_except(int) { return 0; }
 
 LIBC_INLINE int raise_except(int) { return 0; }
 
+LIBC_INLINE int enable_except(int) { return 0; }
+
+LIBC_INLINE int disable_except(int) { return 0; }
+
 LIBC_INLINE int get_round() { return FE_TONEAREST; }
 
 LIBC_INLINE int set_round(int) { return 0; }
 
 LIBC_INLINE int get_env(fenv_t *) { return 0; }
 
 LIBC_INLINE int set_env(const fenv_t *) { return 0; }