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ARM_BX_ALIGN_LOG2

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This commit is contained in:
Roland McGrath 2013-03-13 12:36:53 -07:00
parent ccffb2a2db
commit bb48a26acf
4 changed files with 63 additions and 12 deletions
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4
ports/ChangeLog.arm
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@ -1,5 +1,9 @@
2013-03-13 Roland McGrath <roland@hack.frob.com>
* sysdeps/arm/arm-features.h (ARM_BX_ALIGN_LOG2): New macro.
* sysdeps/arm/memcpy.S: Respect ARM_BX_ALIGN_LOG2.
* sysdeps/arm/memmove.S: Likewise.
* sysdeps/arm/add_n.S: Include <arm-features.h>.
[ARM_ALWAYS_BX]: Don't pop into pc.

13
ports/sysdeps/arm/arm-features.h
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@ -40,4 +40,17 @@
that instructions using pc as a destination register must never be used,
so a "bx" (or "blx") instruction is always required. */
/* The log2 of the minimum alignment required for an address that
is the target of a computed branch (i.e. a "bx" instruction).
A more-specific arm-features.h file may define this to set a more
stringent requirement.
Using this only makes sense for code in ARM mode (where instructions
always have a fixed size of four bytes), or for Thumb-mode code that is
specifically aligning all the related branch targets to match (since
Thumb instructions might be either two or four bytes). */
#ifndef ARM_BX_ALIGN_LOG2
# define ARM_BX_ALIGN_LOG2 2
#endif
#endif /* arm-features.h */

29
ports/sysdeps/arm/memcpy.S
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@ -91,9 +91,9 @@ ENTRY(memcpy)
CALGN( adr r4, 6f )
CALGN( subs r2, r2, r3 ) @ C gets set
#ifndef ARM_ALWAYS_BX
CALGN( add pc, r4, ip )
CALGN( add pc, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
#else
CALGN( add r4, r4, ip )
CALGN( add r4, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
CALGN( bx r4 )
#endif
@ -115,39 +115,56 @@ ENTRY(memcpy)
5: ands ip, r2, #28
rsb ip, ip, #32
#ifndef ARM_ALWAYS_BX
addne pc, pc, ip @ C is always clear here
/* C is always clear here. */
addne pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
b 7f
#else
beq 7f
push {r10}
cfi_adjust_cfa_offset (4)
cfi_rel_offset (r10, 0)
add r10, pc, ip
add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
bx r10
#endif
.p2align ARM_BX_ALIGN_LOG2
6: nop
.p2align ARM_BX_ALIGN_LOG2
ldr r3, [r1], #4
.p2align ARM_BX_ALIGN_LOG2
ldr r4, [r1], #4
.p2align ARM_BX_ALIGN_LOG2
ldr r5, [r1], #4
.p2align ARM_BX_ALIGN_LOG2
ldr r6, [r1], #4
.p2align ARM_BX_ALIGN_LOG2
ldr r7, [r1], #4
.p2align ARM_BX_ALIGN_LOG2
ldr r8, [r1], #4
.p2align ARM_BX_ALIGN_LOG2
ldr lr, [r1], #4
#ifndef ARM_ALWAYS_BX
add pc, pc, ip
add pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
nop
#else
add r10, pc, ip
add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
bx r10
#endif
.p2align ARM_BX_ALIGN_LOG2
nop
.p2align ARM_BX_ALIGN_LOG2
str r3, [r0], #4
.p2align ARM_BX_ALIGN_LOG2
str r4, [r0], #4
.p2align ARM_BX_ALIGN_LOG2
str r5, [r0], #4
.p2align ARM_BX_ALIGN_LOG2
str r6, [r0], #4
.p2align ARM_BX_ALIGN_LOG2
str r7, [r0], #4
.p2align ARM_BX_ALIGN_LOG2
str r8, [r0], #4
.p2align ARM_BX_ALIGN_LOG2
str lr, [r0], #4
#ifdef ARM_ALWAYS_BX

29
ports/sysdeps/arm/memmove.S
View File

@ -107,9 +107,9 @@ ENTRY(memmove)
CALGN( adr r4, 6f )
CALGN( subs r2, r2, ip ) @ C is set here
#ifndef ARM_ALWAYS_BX
CALGN( add pc, r4, ip )
CALGN( add pc, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
#else
CALGN( add r4, r4, ip )
CALGN( add r4, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
CALGN( bx r4 )
#endif
@ -131,39 +131,56 @@ ENTRY(memmove)
5: ands ip, r2, #28
rsb ip, ip, #32
#ifndef ARM_ALWAYS_BX
addne pc, pc, ip @ C is always clear here
/* C is always clear here. */
addne pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
b 7f
#else
beq 7f
push {r10}
cfi_adjust_cfa_offset (4)
cfi_rel_offset (r10, 0)
add r10, pc, ip
add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
bx r10
#endif
.p2align ARM_BX_ALIGN_LOG2
6: nop
.p2align ARM_BX_ALIGN_LOG2
ldr r3, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r4, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r5, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r6, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r7, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r8, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr lr, [r1, #-4]!
#ifndef ARM_ALWAYS_BX
add pc, pc, ip
add pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
nop
#else
add r10, pc, ip
add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
bx r10
#endif
.p2align ARM_BX_ALIGN_LOG2
nop
.p2align ARM_BX_ALIGN_LOG2
str r3, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r4, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r5, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r6, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r7, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r8, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str lr, [r0, #-4]!
#ifdef ARM_ALWAYS_BX