Raymond Toy pushed to branch issue-425-correctly-rounded-math-functions at cmucl / cmucl Commits: 70542bd9 by Raymond Toy at 2025-08-07T17:10:40-07:00 The float-modes type is a 30 bit unsigned byte Since we use a single 32-bit word to set the x87 FP modes, we need at least 30 bits because the top 2 bits are reserved so they shouldn't be set. This is because the control word is in the top 16 bits. Previously, the float-modes type was an (unsigned-byte 24), which is too small now. - - - - - 5edb2d90 by Raymond Toy at 2025-08-08T06:49:06-07:00 Fix #426: Define float-modes type correctly The definition of `float-modes` is `(unsigned-byte 24)`. This is too small if we are trying to set the precision control field for x87 via `(setf (x86::x87-floating-point-modes) ...)`. The field needs to be at least 30 bits to that we can assign values for the x87 control and status words. Thus, set the type to `(unsigned-byte 32)`. - - - - - 387ed142 by Raymond Toy at 2025-08-08T07:11:42-07:00 Add test for (setf (x86::x87-floating-point-modes)) - - - - - 4d1f287c by Raymond Toy at 2025-08-08T18:29:40-07:00 Merge branch 'issue-426-fix-float-modes-type-def' into issue-425-correctly-rounded-math-functions - - - - - 84ee222f by Raymond Toy at 2025-08-08T19:59:15-07:00 lisp.a needs to have the core math routines too. - - - - - f47f8f07 by Raymond Toy at 2025-08-08T20:00:17-07:00 Set the x87 precision to double when calling out to C When we call out to C, we save the x87 FPU control word. Then update the FPU control to have the precision set to double (53-bit) precision. This is needed for the core-math routines that depend on the x87 precision control to be double. When the function returns, we restore the original x87 control word. - - - - - 4 changed files: - src/compiler/x86/float-sse2.lisp - src/compiler/x86/sse2-c-call.lisp - src/lisp/GNUmakefile - tests/float.lisp Changes: ===================================== src/compiler/x86/float-sse2.lisp ===================================== @@ -1265,7 +1265,7 @@  ;;;; Float mode hackery: -(deftype float-modes () '(unsigned-byte 24)) +(deftype float-modes () '(unsigned-byte 30)) ;; For the record, here is the format of the MXCSR register. ;; ===================================== src/compiler/x86/sse2-c-call.lisp ===================================== @@ -36,12 +36,23 @@ :from :eval :to :result) edx) (:temporary (:sc single-stack) temp-single) (:temporary (:sc double-stack) temp-double) + (:temporary (:sc unsigned-stack) save-fpu-cw) + (:temporary (:sc unsigned-stack) fpu-cw) (:node-var node) (:vop-var vop) (:save-p t) - (:ignore args ecx edx) + (:ignore args ecx #+nil edx) (:guard (backend-featurep :sse2)) - (:generator 0 + (:generator 0 + ;; Save the x87 FPU control word. Then modify it to set the + ;; precision bits to double (2). + (inst fnstcw save-fpu-cw) + (move edx save-fpu-cw) + (inst and edx (dpb 0 (byte 2 8) #xffff)) ; Zap the precision control bits + (inst or edx (dpb 2 (byte 2 8) 0)) ; Set precision control to double + (move fpu-cw edx) + (inst fldcw fpu-cw) ; New CW + (cond ((policy node (> space speed)) (move eax function) (inst call (make-fixup (extern-alien-name "call_into_c") :foreign))) @@ -63,7 +74,9 @@ (inst movss xmm0-tn (ea-for-sf-stack temp-single))) (double-reg (inst fstpd (ea-for-df-stack temp-double)) - (inst movsd xmm0-tn (ea-for-df-stack temp-double))))))) + (inst movsd xmm0-tn (ea-for-df-stack temp-double))))) + ;; Restore the x87 FPU control settings + (inst fldcw save-fpu-cw))) (define-vop (alloc-number-stack-space) (:info amount) ===================================== src/lisp/GNUmakefile ===================================== @@ -83,7 +83,7 @@ lisp: ${OBJS} ${CORE64_OBJS} version.o # Create a library out of all the object files so we can build an # executable. However, we need to remove exec-init.o from the library lisp.a: version.o ${OBJS} ${CORE64_OBJS} ${EXEC_FINAL_OBJ} - $(AR) crs lisp.a ${OBJS} version.o + $(AR) crs lisp.a ${OBJS} ${CORE64_OBJS} version.o ifneq (${EXEC_FINAL_OBJ},) $(AR) d lisp.a exec-init.o endif ===================================== tests/float.lisp ===================================== @@ -333,3 +333,13 @@ (declare (ignore c)) (values (invoke-restart 'lisp::largest-float))))) (read-from-string string)))))) + +#+x86 +(define-test x87-set-floating-point-modes + (:tag :issues) + (let ((new-mode (setf (x86::x87-floating-point-modes) + (dpb 2 (byte 2 24) + (x86::x87-floating-point-modes))))) + (assert-true (typep new-mode 'x86::float-modes)) + (assert-equal new-mode (setf (x86::x87-floating-point-modes) new-mode)))) + View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/compare/a38612dca7b478767b47a6a... -- View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/compare/a38612dca7b478767b47a6a... You're receiving this email because of your account on gitlab.common-lisp.net.