[Git][cmucl/cmucl][issue-86-save-fpu-state-on-entry-to-alloc] Save just the xmm registers

[Raymond Toy]

Raymond Toy pushed to branch issue-86-save-fpu-state-on-entry-to-alloc at cmucl / cmucl


Commits:
17144e16 by Raymond Toy at 2020-08-28T16:23:59-07:00
Save just the xmm registers

Instead of saving the entire FPU state, we really only need to save
the xmm registers.

- - - - -


1 changed file:

- src/lisp/x86-assem.S


Changes:

=====================================
src/lisp/x86-assem.S
=====================================
@@ -404,22 +404,39 @@ FUNCDEF(alloc_overflow_sse2)
 ENDFUNC(alloc_overflow_sse2)	
 #else
 FUNCDEF(alloc_overflow_sse2)
-	# Need 512 bytes for the fpu save area, space to save ecx and edx, 
-	# space for mxcsr, a temp, and one arg to pass to alloc.  That's 
-	# 512 + 20.  But the save area needs to be 16-byte aligned, so
-	# allocate 512 + 32 bytes.  The fpu area will be at offset 32.
+	# Need 8*16 bytes for the xmm registers, and space to save ecx
+	# and edx, space for mxcsr, a temp, and one arg to pass to alloc.
+	# That's 8*16 + 5*4 = 148 bytes.  Might as well have a few
+	# more so the xmm0 area is 16-byte aligned. That makes it 160
+	# bytes.
 	#
 	# Stack looks like:
 	#
-	#      +544 -> end
-	#      +32  -> fpu save
-        #      +20  -> unused
+	#      +160
+	#      +144 -> xmm7
+	#      +128 -> xmm6
+	#      +112 -> xmm5
+	#      +96  -> xmm4
+	#      +80  -> xmm3
+	#      +64  -> xmm2
+	#      +48  -> xmm1
+	#      +32  -> xmm0
+	#      +20  -> unused
 	#      +16  -> temp
 	#      +12  -> mxcsr
 	#      + 8  -> save ecx
 	#      + 4  -> save edx
 	#  esp + 0  -> arg for alloc
-	STACK_PROLOGUE(32+512)
+	STACK_PROLOGUE(160)
+	movapd  %xmm0, (32 + 0*16)(%esp)
+	movapd  %xmm1, (32 + 1*16)(%esp)
+	movapd  %xmm2, (32 + 2*16)(%esp)
+	movapd  %xmm3, (32 + 3*16)(%esp)
+	movapd  %xmm4, (32 + 4*16)(%esp)
+	movapd  %xmm5, (32 + 5*16)(%esp)
+	movapd  %xmm6, (32 + 6*16)(%esp)
+	movapd  %xmm7, (32 + 7*16)(%esp)
+
 	movl	%ecx, 8(%esp)	# Save ecx and edx registers
 	movl	%edx, 4(%esp)
 	stmxcsr 12(%esp)	# Save MXCSR
@@ -430,16 +447,21 @@ FUNCDEF(alloc_overflow_sse2)
 	ldmxcsr 16(%esp)	# Get new mxcsr value
 	movl	%eax, (%esp)	# Put size on stack for first arg to alloc()
 
-	# Save all FPU regs because we don't know what's in use by lisp.
-	fxsave	32(%esp)
-	
 	call	GNAME(alloc)
 
-	fxrstor 32(%esp)
-
 	movl	4(%esp), %edx	# Restore edx and ecx registers.  eax has the return value.
 	movl	8(%esp), %ecx
 	ldmxcsr	12(%esp)
+
+	movapd  (32 + 0*16)(%esp), %xmm0
+	movapd  (32 + 1*16)(%esp), %xmm1
+	movapd  (32 + 2*16)(%esp), %xmm2
+	movapd  (32 + 3*16)(%esp), %xmm3
+	movapd  (32 + 4*16)(%esp), %xmm4
+	movapd  (32 + 5*16)(%esp), %xmm5
+	movapd  (32 + 6*16)(%esp), %xmm6
+	movapd  (32 + 7*16)(%esp), %xmm7
+
 	STACK_EPILOGUE
 	ret
 ENDFUNC(alloc_overflow_sse2)	



View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/17144e16d4f7578644fac5750d7d197914fd474a

-- 
View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/17144e16d4f7578644fac5750d7d197914fd474a
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