//===----------------------Hexagon builtin routine ------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Functions that implement common sequences in function prologues and epilogues
// used to save code size
.macro FUNCTION_BEGIN name
.text
.globl \name
.type \name, @function
.falign
\name:
.endm
.macro FUNCTION_END name
.size \name, . - \name
.endm
.macro FALLTHROUGH_TAIL_CALL name0 name1
.size \name0, . - \name0
.globl \name1
.type \name1, @function
.falign
\name1:
.endm
// Save r27:26 at fp+#-8, r25:24 at fp+#-16, r23:22 at fp+#-24, r21:20 at
// fp+#-32, r19:18 at fp+#-40, and r17:16 at fp+#-48.
// The compiler knows that the __save_* functions clobber LR. No other
// registers should be used without informing the compiler.
// Since we can only issue one store per packet, we don't hurt performance by
// simply jumping to the right point in this sequence of stores.
FUNCTION_BEGIN __save_r27_through_r16
memd(fp+#-48) = r17:16
FALLTHROUGH_TAIL_CALL __save_r27_through_r16 __save_r27_through_r18
memd(fp+#-40) = r19:18
FALLTHROUGH_TAIL_CALL __save_r27_through_r18 __save_r27_through_r20
memd(fp+#-32) = r21:20
FALLTHROUGH_TAIL_CALL __save_r27_through_r20 __save_r27_through_r22
memd(fp+#-24) = r23:22
FALLTHROUGH_TAIL_CALL __save_r27_through_r22 __save_r27_through_r24
memd(fp+#-16) = r25:24
{
memd(fp+#-8) = r27:26
jumpr lr
}
FUNCTION_END __save_r27_through_r24
// For each of the *_before_sibcall functions, jumpr lr is executed in parallel
// with deallocframe. That way, the return gets the old value of lr, which is
// where these functions need to return, and at the same time, lr gets the value
// it needs going into the sibcall.
FUNCTION_BEGIN __restore_r27_through_r20_and_deallocframe_before_sibcall
{
r21:20 = memd(fp+#-32)
r23:22 = memd(fp+#-24)
}
FALLTHROUGH_TAIL_CALL __restore_r27_through_r20_and_deallocframe_before_sibcall __restore_r27_through_r24_and_deallocframe_before_sibcall
{
r25:24 = memd(fp+#-16)
jump __restore_r27_through_r26_and_deallocframe_before_sibcall
}
FUNCTION_END __restore_r27_through_r24_and_deallocframe_before_sibcall
FUNCTION_BEGIN __restore_r27_through_r16_and_deallocframe_before_sibcall
r17:16 = memd(fp+#-48)
FALLTHROUGH_TAIL_CALL __restore_r27_through_r16_and_deallocframe_before_sibcall __restore_r27_through_r18_and_deallocframe_before_sibcall
{
r19:18 = memd(fp+#-40)
r21:20 = memd(fp+#-32)
}
FALLTHROUGH_TAIL_CALL __restore_r27_through_r18_and_deallocframe_before_sibcall __restore_r27_through_r22_and_deallocframe_before_sibcall
{
r23:22 = memd(fp+#-24)
r25:24 = memd(fp+#-16)
}
FALLTHROUGH_TAIL_CALL __restore_r27_through_r22_and_deallocframe_before_sibcall __restore_r27_through_r26_and_deallocframe_before_sibcall
{
r27:26 = memd(fp+#-8)
deallocframe
jumpr lr
}
FUNCTION_END __restore_r27_through_r26_and_deallocframe_before_sibcall
// Here we use the extra load bandwidth to restore LR early, allowing the return
// to occur in parallel with the deallocframe.
FUNCTION_BEGIN __restore_r27_through_r16_and_deallocframe
{
r17:16 = memd(fp+#-48)
r19:18 = memd(fp+#-40)
}
FALLTHROUGH_TAIL_CALL __restore_r27_through_r16_and_deallocframe __restore_r27_through_r20_and_deallocframe
{
r21:20 = memd(fp+#-32)
r23:22 = memd(fp+#-24)
}
FALLTHROUGH_TAIL_CALL __restore_r27_through_r20_and_deallocframe __restore_r27_through_r24_and_deallocframe
{
lr = memw(fp+#4)
r25:24 = memd(fp+#-16)
}
{
r27:26 = memd(fp+#-8)
deallocframe
jumpr lr
}
FUNCTION_END __restore_r27_through_r24_and_deallocframe
// Here the load bandwidth is maximized for all three functions.
FUNCTION_BEGIN __restore_r27_through_r18_and_deallocframe
{
r19:18 = memd(fp+#-40)
r21:20 = memd(fp+#-32)
}
FALLTHROUGH_TAIL_CALL __restore_r27_through_r18_and_deallocframe __restore_r27_through_r22_and_deallocframe
{
r23:22 = memd(fp+#-24)
r25:24 = memd(fp+#-16)
}
FALLTHROUGH_TAIL_CALL __restore_r27_through_r22_and_deallocframe __restore_r27_through_r26_and_deallocframe
{
r27:26 = memd(fp+#-8)
deallocframe
}
jumpr lr
FUNCTION_END __restore_r27_through_r26_and_deallocframe
Codebase Browser
llvm