Raymond Toy pushed to branch issue-355-solaris-x86-fp-trap-handler at cmucl / cmucl

Commits: 5db3c51f by Raymond Toy at 2024-09-06T15:39:33-07:00 Solaris/x86 needs its own with-float-traps macro

For Solaris/x86, `with-float-traps` needs to handle the x87 and sse2 mode bits separately.

The previous version used the merged value returned by `vm:floating-point-modes`. If the original mode had, say, the overflow flag set, when the macro restored the modes, the overflow flag was also set for x87 and sse2. Later on this can cause an expected overflow because the x87 mode has overflow set along with the sse2 mode. This shows up in the SIGFPE handler.

To fix this, we handle the x87 and sse2 mode bits separately. Hence, we don't spuriously add back the overflow bit for x87 which didn't have it previously set.

- - - - -

1 changed file:

- src/code/float-trap.lisp

Changes:

===================================== src/code/float-trap.lisp ===================================== @@ -568,6 +568,7 @@ (alien:sap-alien scp (* unix:sigcontext)) (logandc2 sse2-modes trap-bit)))))))

+#-(and solaris x86) (macrolet ((with-float-traps (name merge-traps docstring) ;; Define macros to enable or disable floating-point @@ -631,6 +632,71 @@ accrued exceptions are cleared at the start of the body to support their testing within, and restored on exit."))

+#+(and solaris x86) +(macrolet + ((with-float-traps (name merge-traps docstring) + ;; Define macros to enable or disable floating-point + ;; exceptions. Masked exceptions and enabled exceptions only + ;; differ whether we AND in the bits or OR them, respectively. + ;; MERGE-TRAPS is the logical operation to merge the traps with + ;; the current floating-point mode. Thus, use and MERGE-EXCEPTIONS is the + ;; logical operation to merge the exceptions (sticky bits) with + ;; the current mode. + (let ((macro-name (symbolicate "WITH-FLOAT-TRAPS-" name))) + `(progn + (defmacro ,macro-name (traps &body body) + ,docstring + (let* ((sse2-trap-mask (dpb (lognot (float-trap-mask traps)) + float-traps-byte #xffffffff)) + ;; The x87 trap masks are ordered the same as + ;; sse2 trap masks, but are located in a + ;; different part of the word. + (x87-trap-mask (dpb (lognot (ash (float-trap-mask traps) 16)) + float-traps-byte #xffffffff)) + (exception-mask (dpb (lognot (vm::float-trap-mask traps)) + float-sticky-bits #xffffffff)) + (orig-modes-x87 (gensym "ORIG-MODES-X87-")) + (orig-modes-sse2 (gensym "ORIG-MODES-SSE2-"))) + `(let ((,orig-modes-x87 (x87-floating-point-modes)) + (,orig-modes-sse2 (sse2-floating-point-modes))) + (format t "In W-F-T:~%") + (format t " orig x87 modes: ~32,'0b~%" ,orig-modes-x87) + (format t " orig sse2 modes: ~32,'0b~%" ,orig-modes-sse2) + (unwind-protect + (progn + (setf (x87-floating-point-modes) + (ldb (byte 32 0) + (logand (,',merge-traps ,orig-modes-x87 ,x87-trap-mask) + ,exception-mask))) + (setf (sse2-floating-point-modes) + (ldb (byte 32 0) + (logand (,',merge-traps ,orig-modes-sse2 ,sse2-trap-mask) + ,exception-mask))) + (format t " masked x87 modes: ~32,'0b~%" (x87-floating-point-modes)) + (format t " masked sse2 modes: ~32,'0b~%" (sse2-floating-point-modes)) + ,@body) + ;; Restore the modes exactly as they were. + (setf (x87-floating-point-modes) ,orig-modes-x87) + (setf (sse2-floating-point-modes) ,orig-modes-sse2))))))))) + + ;; WITH-FLOAT-TRAPS-MASKED -- Public + (with-float-traps masked logand + _N"Execute BODY with the floating point exceptions listed in TRAPS + masked (disabled). TRAPS should be a list of possible exceptions + which includes :UNDERFLOW, :OVERFLOW, :INEXACT, :INVALID and + :DIVIDE-BY-ZERO and on the X86 :DENORMALIZED-OPERAND. The respective + accrued exceptions are cleared at the start of the body to support + their testing within, and restored on exit.") + + ;; WITH-FLOAT-TRAPS-ENABLED -- Public + (with-float-traps enabled logorc2 + _N"Execute BODY with the floating point exceptions listed in TRAPS + enabled. TRAPS should be a list of possible exceptions which + includes :UNDERFLOW, :OVERFLOW, :INEXACT, :INVALID and + :DIVIDE-BY-ZERO and on the X86 :DENORMALIZED-OPERAND. The respective + accrued exceptions are cleared at the start of the body to support + their testing within, and restored on exit.")) + (defmacro with-float-rounding-mode ((rounding-mode) &body body) _N"Execute BODY with the floating-point rounding mode set to ROUNDING-MODE. ROUNDING-MODE must be a one:

View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/5db3c51f755738d221eae416...