From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Cc: Paul E Murphy <murphyp@linux.ibm.com>
Subject: [PATCH v3] powerpc: Fix __fesetround_inline_nocheck on POWER9+ (BZ 31682)
Date: Tue, 7 May 2024 09:19:48 -0300 [thread overview]
Message-ID: <20240507122016.2645778-1-adhemerval.zanella@linaro.org> (raw)
The e68b1151f7460d5fa88c3a567c13f66052da79a7 commit changed the
__fesetround_inline_nocheck implementation to use mffscrni
(through __fe_mffscrn) instead of mtfsfi. For generic powerpc
ceil/floor/trunc, the function is supposed to disable the
floating-point inexact exception enablebbit, however mffscrni
does not change any exception enable bits.
This patch fixes by reverting the optimization for the
__fesetround_inline_nocheck.
Checked on powerpc-linux-gnu.
---
sysdeps/powerpc/fpu/fenv_libc.h | 16 +++++-----------
sysdeps/powerpc/fpu/round_to_integer.h | 6 +++---
2 files changed, 8 insertions(+), 14 deletions(-)
diff --git a/sysdeps/powerpc/fpu/fenv_libc.h b/sysdeps/powerpc/fpu/fenv_libc.h
index f9167056a8..0a06e4486b 100644
--- a/sysdeps/powerpc/fpu/fenv_libc.h
+++ b/sysdeps/powerpc/fpu/fenv_libc.h
@@ -182,19 +182,13 @@ __fesetround_inline (int round)
return 0;
}
-/* Same as __fesetround_inline, however without runtime check to use DFP
- mtfsfi syntax (as relax_fenv_state) or if round value is valid. */
+/* Same as __fesetround_inline, and it also disable the floating-point
+ inexact execption (bit 60 - XE, assuming NI is 0). It does not check
+ if ROUND is a valid value. */
static inline void
-__fesetround_inline_nocheck (const int round)
+__fesetround_inline_disable_inexact (const int round)
{
-#ifdef _ARCH_PWR9
- __fe_mffscrn (round);
-#else
- if (__glibc_likely (GLRO(dl_hwcap2) & PPC_FEATURE2_ARCH_3_00))
- __fe_mffscrn (round);
- else
- asm volatile ("mtfsfi 7,%0" : : "n" (round));
-#endif
+ asm volatile ("mtfsfi 7,%0" : : "n" (round));
}
#define FPSCR_MASK(bit) (1 << (31 - (bit)))
diff --git a/sysdeps/powerpc/fpu/round_to_integer.h b/sysdeps/powerpc/fpu/round_to_integer.h
index b68833640f..6996519c61 100644
--- a/sysdeps/powerpc/fpu/round_to_integer.h
+++ b/sysdeps/powerpc/fpu/round_to_integer.h
@@ -42,14 +42,14 @@ set_fenv_mode (enum round_mode mode)
switch (mode)
{
case CEIL:
- __fesetround_inline_nocheck (FE_UPWARD);
+ __fesetround_inline_disable_inexact (FE_UPWARD);
break;
case FLOOR:
- __fesetround_inline_nocheck (FE_DOWNWARD);
+ __fesetround_inline_disable_inexact (FE_DOWNWARD);
break;
case TRUNC:
case ROUND:
- __fesetround_inline_nocheck (FE_TOWARDZERO);
+ __fesetround_inline_disable_inexact (FE_TOWARDZERO);
break;
case NEARBYINT:
/* Disable FE_INEXACT exception */
--
2.43.0
next reply other threads:[~2024-05-07 12:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 12:19 Adhemerval Zanella [this message]
2024-05-07 12:48 ` Andreas Schwab
2024-05-07 12:52 ` Adhemerval Zanella Netto
2024-05-08 18:25 ` Paul E Murphy
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