From 6640579610856168a64e12c097ce012c46648e00 Mon Sep 17 00:00:00 2001
From: Justin Hibbits <jhibbits@FreeBSD.org>
Date: Wed, 5 May 2021 09:20:56 -0500
Subject: [PATCH] msun fixes for SPE

Summary:
Fix FPU exception management for powerpcspe.  Bits are in a different place from
the standard FPSCR, so we need to handle the shifting differences.  Also,
there's no concept of a "software exception" raise, so we need to do exceptional
math to trigger the exception from software.

Reviewed By: alfredo
Differential Revision: https://reviews.freebsd.org/D22824
---
 lib/msun/powerpc/fenv.c | 30 ++++++++++++++++++++++++++++++
 lib/msun/powerpc/fenv.h | 19 ++++++++++++++++++-
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/lib/msun/powerpc/fenv.c b/lib/msun/powerpc/fenv.c
index b7e611ed99a0..7f7d98515995 100644
--- a/lib/msun/powerpc/fenv.c
+++ b/lib/msun/powerpc/fenv.c
@@ -30,6 +30,10 @@
 
 #define	__fenv_static
 #include "fenv.h"
+#ifdef __SPE__
+#include <sys/types.h>
+#include <machine/spr.h>
+#endif
 
 #ifdef __GNUC_GNU_INLINE__
 #error "This file must be compiled with C99 'inline' semantics"
@@ -40,7 +44,9 @@ const fenv_t __fe_dfl_env = 0x00000000;
 extern inline int feclearexcept(int __excepts);
 extern inline int fegetexceptflag(fexcept_t *__flagp, int __excepts);
 extern inline int fesetexceptflag(const fexcept_t *__flagp, int __excepts);
+#ifndef __SPE__
 extern inline int feraiseexcept(int __excepts);
+#endif
 extern inline int fetestexcept(int __excepts);
 extern inline int fegetround(void);
 extern inline int fesetround(int __round);
@@ -48,3 +54,27 @@ extern inline int fegetenv(fenv_t *__envp);
 extern inline int feholdexcept(fenv_t *__envp);
 extern inline int fesetenv(const fenv_t *__envp);
 extern inline int feupdateenv(const fenv_t *__envp);
+
+#ifdef __SPE__
+#define	PMAX	0x7f7fffff
+#define	PMIN	0x00800000
+int	feraiseexcept(int __excepts)
+{
+	uint32_t spefscr;
+
+	spefscr = mfspr(SPR_SPEFSCR);
+	mtspr(SPR_SPEFSCR, spefscr | (__excepts & FE_ALL_EXCEPT));
+
+	if (__excepts & FE_INVALID)
+		__asm __volatile ("efsdiv %0, %0, %1" :: "r"(0), "r"(0));
+	if (__excepts & FE_DIVBYZERO)
+		__asm __volatile ("efsdiv %0, %0, %1" :: "r"(1.0f), "r"(0));
+	if (__excepts & FE_UNDERFLOW)
+		__asm __volatile ("efsmul %0, %0, %0" :: "r"(PMIN));
+	if (__excepts & FE_OVERFLOW)
+		__asm __volatile ("efsadd %0, %0, %0" :: "r"(PMAX));
+	if (__excepts & FE_INEXACT)
+		__asm __volatile ("efssub %0, %0, %1" :: "r"(PMIN), "r"(1.0f));
+	return (0);
+}
+#endif
diff --git a/lib/msun/powerpc/fenv.h b/lib/msun/powerpc/fenv.h
index d054220678c2..21a70df3d104 100644
--- a/lib/msun/powerpc/fenv.h
+++ b/lib/msun/powerpc/fenv.h
@@ -42,6 +42,17 @@ typedef	__uint32_t	fenv_t;
 typedef	__uint32_t	fexcept_t;
 
 /* Exception flags */
+#ifdef __SPE__
+#define FE_OVERFLOW	0x00000100
+#define FE_UNDERFLOW	0x00000200
+#define FE_DIVBYZERO	0x00000400
+#define FE_INVALID	0x00000800
+#define FE_INEXACT	0x00001000
+
+#define	FE_ALL_INVALID	FE_INVALID
+
+#define	_FPUSW_SHIFT	6
+#else
 #define	FE_INEXACT	0x02000000
 #define	FE_DIVBYZERO	0x04000000
 #define	FE_UNDERFLOW	0x08000000
@@ -67,6 +78,9 @@ typedef	__uint32_t	fexcept_t;
 #define	FE_ALL_INVALID	(FE_VXCVI | FE_VXSQRT | FE_VXSOFT | FE_VXVC | \
 			 FE_VXIMZ | FE_VXZDZ | FE_VXIDI | FE_VXISI | \
 			 FE_VXSNAN | FE_INVALID)
+
+#define	_FPUSW_SHIFT	22
+#endif
 #define	FE_ALL_EXCEPT	(FE_DIVBYZERO | FE_INEXACT | \
 			 FE_ALL_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
 
@@ -85,7 +99,6 @@ extern const fenv_t	__fe_dfl_env;
 #define	FE_DFL_ENV	(&__fe_dfl_env)
 
 /* We need to be able to map status flag positions to mask flag positions */
-#define	_FPUSW_SHIFT	22
 #define	_ENABLE_MASK	((FE_DIVBYZERO | FE_INEXACT | FE_INVALID | \
 			 FE_OVERFLOW | FE_UNDERFLOW) >> _FPUSW_SHIFT)
 
@@ -156,6 +169,9 @@ fesetexceptflag(const fexcept_t *__flagp, int __excepts)
 	return (0);
 }
 
+#ifdef __SPE__
+extern int	feraiseexcept(int __excepts);
+#else
 __fenv_static inline int
 feraiseexcept(int __excepts)
 {
@@ -168,6 +184,7 @@ feraiseexcept(int __excepts)
 	__mtfsf(__r);
 	return (0);
 }
+#endif
 
 __fenv_static inline int
 fetestexcept(int __excepts)