[newlib-cygwin/main] RISC-V: Fix floating-point environment support for soft float

[newlib-cygwin/main] RISC-V: Fix floating-point environment support for soft float

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=963d6c79ead3941b399e3549bc753c2cb90ab79b

commit 963d6c79ead3941b399e3549bc753c2cb90ab79b
Author:     Maciej W. Rozycki <macro@embecosm.com>
AuthorDate: Fri Jan 27 08:53:35 2023 +0000
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Fri Jan 27 14:25:44 2023 +0100

    RISC-V: Fix floating-point environment support for soft float
    
    We don't have floating-point exception or non-default rounding mode
    support for the RISC-V soft-float environment, `feraiseexcept' and
    `fesetround' do nothing unless the `__riscv_flen' macro has been set.
    Therefore following ISO C language requirements[1] only define macros
    for soft float that correspond to actually supported floating-point
    environment features, removing failures from GCC testing such as:
    
    FAIL: gcc.dg/torture/fp-int-convert-timode-3.c   -O0  execution test
    FAIL: gcc.dg/torture/fp-int-convert-timode-4.c   -O0  execution test
    
    References:
    
    [1] "Programming languages -- C", ISO/IEC 9899:2023, working draft --
        September 3, 2022, Section 7.6 "Floating-point environment <fenv.h>"
    
    Fixes: 7040b2de0883 ("Add RISC-V port for libm")
    Signed-off-by: Maciej W. Rozycki <macro@embecosm.com>

Diff:
---
 newlib/libc/machine/riscv/sys/fenv.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/newlib/libc/machine/riscv/sys/fenv.h b/newlib/libc/machine/riscv/sys/fenv.h
index 6cbd321f3499..772f3833f4a4 100644
--- a/newlib/libc/machine/riscv/sys/fenv.h
+++ b/newlib/libc/machine/riscv/sys/fenv.h
@@ -14,6 +14,8 @@
 
 #include <stddef.h>
 
+#if __riscv_flen
+
 /* Per "The RISC-V Instruction Set Manual: Volume I: User-Level ISA:
  * Version 2.1", Section 8.2, "Floating-Point Control and Status
  * Register":
@@ -69,6 +71,13 @@
  * floating-point unit."
  */
 
+#else /* !__riscv_flen */
+
+#define FE_ALL_EXCEPT   0x00000000
+#define FE_TONEAREST    0x00000000
+
+#endif /* !__riscv_flen */
+
 typedef size_t fenv_t;
 typedef size_t fexcept_t;
 extern const fenv_t fe_dfl_env;