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From 0dbdfb7918d0b0cfcb8883b24c1291574bf5bb7c Mon Sep 17 00:00:00 2001
From: Max Filippov <jcmvbkbc@gmail.com>
Date: Tue, 2 Apr 2019 14:32:42 -0700
Subject: [PATCH] gas: use literals/const16 for xtensa loop relaxation
Loop opcode relaxation that uses addi/addmi doesn't work well with other
relaxations that may cause code movement. Instead of encoding fixed loop
end offset in the relaxed sequence use l32r or a pair of const16 to load
loop end address. This way the address of the loop end gets a relocation
record and it gets updated appropriately.
gas/
2019-04-02 Max Filippov <jcmvbkbc@gmail.com>
* config/tc-xtensa.c (convert_frag_immed): Drop
convert_frag_immed_finish_loop invocation.
(convert_frag_immed_finish_loop): Drop declaration and
definition.
* config/xtensa-relax.c (widen_spec_list): Replace loop
widening that uses addi/addmi with widening that uses l32r
and const16.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
gas/config/tc-xtensa.c | 120 ----------------------------------------------
gas/config/xtensa-relax.c | 77 ++++++++++++++++++++---------
2 files changed, 55 insertions(+), 142 deletions(-)
diff --git a/gas/config/tc-xtensa.c b/gas/config/tc-xtensa.c
index 3bdbbc931cfc..0cc06361cf6f 100644
--- a/gas/config/tc-xtensa.c
+++ b/gas/config/tc-xtensa.c
@@ -10668,7 +10668,6 @@ convert_frag_fill_nop (fragS *fragP)
static fixS *fix_new_exp_in_seg
(segT, subsegT, fragS *, int, int, expressionS *, int,
bfd_reloc_code_real_type);
-static void convert_frag_immed_finish_loop (segT, fragS *, TInsn *);
static void
convert_frag_immed (segT segP,
@@ -10910,9 +10909,6 @@ convert_frag_immed (segT segP,
}
}
- if (expanded && xtensa_opcode_is_loop (isa, orig_tinsn.opcode) == 1)
- convert_frag_immed_finish_loop (segP, fragP, &orig_tinsn);
-
if (expanded && is_direct_call_opcode (orig_tinsn.opcode))
{
/* Add an expansion note on the expanded instruction. */
@@ -10949,122 +10945,6 @@ fix_new_exp_in_seg (segT new_seg,
}
-/* Relax a loop instruction so that it can span loop >256 bytes.
-
- loop as, .L1
- .L0:
- rsr as, LEND
- wsr as, LBEG
- addi as, as, lo8 (label-.L1)
- addmi as, as, mid8 (label-.L1)
- wsr as, LEND
- isync
- rsr as, LCOUNT
- addi as, as, 1
- .L1:
- <<body>>
- label:
-*/
-
-static void
-convert_frag_immed_finish_loop (segT segP, fragS *fragP, TInsn *tinsn)
-{
- TInsn loop_insn;
- TInsn addi_insn;
- TInsn addmi_insn;
- unsigned long target;
- static xtensa_insnbuf insnbuf = NULL;
- unsigned int loop_length, loop_length_hi, loop_length_lo;
- xtensa_isa isa = xtensa_default_isa;
- addressT loop_offset;
- addressT addi_offset = 9;
- addressT addmi_offset = 12;
- fragS *next_fragP;
- int target_count;
-
- if (!insnbuf)
- insnbuf = xtensa_insnbuf_alloc (isa);
-
- /* Get the loop offset. */
- loop_offset = get_expanded_loop_offset (tinsn->opcode);
-
- /* Validate that there really is a LOOP at the loop_offset. Because
- loops are not bundleable, we can assume that the instruction will be
- in slot 0. */
- tinsn_from_chars (&loop_insn, fragP->fr_opcode + loop_offset, 0);
- tinsn_immed_from_frag (&loop_insn, fragP, 0);
-
- gas_assert (xtensa_opcode_is_loop (isa, loop_insn.opcode) == 1);
- addi_offset += loop_offset;
- addmi_offset += loop_offset;
-
- gas_assert (tinsn->ntok == 2);
- if (tinsn->tok[1].X_op == O_constant)
- target = tinsn->tok[1].X_add_number;
- else if (tinsn->tok[1].X_op == O_symbol)
- {
- /* Find the fragment. */
- symbolS *sym = tinsn->tok[1].X_add_symbol;
- gas_assert (S_GET_SEGMENT (sym) == segP
- || S_GET_SEGMENT (sym) == absolute_section);
- target = (S_GET_VALUE (sym) + tinsn->tok[1].X_add_number);
- }
- else
- {
- as_bad (_("invalid expression evaluation type %d"), tinsn->tok[1].X_op);
- target = 0;
- }
-
- loop_length = target - (fragP->fr_address + fragP->fr_fix);
- loop_length_hi = loop_length & ~0x0ff;
- loop_length_lo = loop_length & 0x0ff;
- if (loop_length_lo >= 128)
- {
- loop_length_lo -= 256;
- loop_length_hi += 256;
- }
-
- /* Because addmi sign-extends the immediate, 'loop_length_hi' can be at most
- 32512. If the loop is larger than that, then we just fail. */
- if (loop_length_hi > 32512)
- as_bad_where (fragP->fr_file, fragP->fr_line,
- _("loop too long for LOOP instruction"));
-
- tinsn_from_chars (&addi_insn, fragP->fr_opcode + addi_offset, 0);
- gas_assert (addi_insn.opcode == xtensa_addi_opcode);
-
- tinsn_from_chars (&addmi_insn, fragP->fr_opcode + addmi_offset, 0);
- gas_assert (addmi_insn.opcode == xtensa_addmi_opcode);
-
- set_expr_const (&addi_insn.tok[2], loop_length_lo);
- tinsn_to_insnbuf (&addi_insn, insnbuf);
-
- fragP->tc_frag_data.is_insn = TRUE;
- xtensa_insnbuf_to_chars
- (isa, insnbuf, (unsigned char *) fragP->fr_opcode + addi_offset, 0);
-
- set_expr_const (&addmi_insn.tok[2], loop_length_hi);
- tinsn_to_insnbuf (&addmi_insn, insnbuf);
- xtensa_insnbuf_to_chars
- (isa, insnbuf, (unsigned char *) fragP->fr_opcode + addmi_offset, 0);
-
- /* Walk through all of the frags from here to the loop end
- and mark them as no_transform to keep them from being modified
- by the linker. If we ever have a relocation for the
- addi/addmi of the difference of two symbols we can remove this. */
-
- target_count = 0;
- for (next_fragP = fragP; next_fragP != NULL;
- next_fragP = next_fragP->fr_next)
- {
- next_fragP->tc_frag_data.is_no_transform = TRUE;
- if (next_fragP->tc_frag_data.is_loop_target)
- target_count++;
- if (target_count == 2)
- break;
- }
-}
-
/* A map that keeps information on a per-subsegment basis. This is
maintained during initial assembly, but is invalid once the
diff --git a/gas/config/xtensa-relax.c b/gas/config/xtensa-relax.c
index cb296ed85ed2..daf15d52c259 100644
--- a/gas/config/xtensa-relax.c
+++ b/gas/config/xtensa-relax.c
@@ -87,13 +87,7 @@
when the first and second operands are not the same as specified
by the "| %at!=%as" precondition clause.
{"l32i %at,%as,%imm | %at!=%as",
- "LITERAL %imm; l32r %at,%LITERAL; add %at,%at,%as; l32i %at,%at,0"}
-
- There is special case for loop instructions here, but because we do
- not currently have the ability to represent the difference of two
- symbols, the conversion requires special code in the assembler to
- write the operands of the addi/addmi pair representing the
- difference of the old and new loop end label. */
+ "LITERAL %imm; l32r %at,%LITERAL; add %at,%at,%as; l32i %at,%at,0"} */
#include "as.h"
#include "xtensa-isa.h"
@@ -306,44 +300,83 @@ static string_pattern_pair widen_spec_list[] =
{"l32i %at,%as,%imm | %at!=%as ? IsaUseConst16",
"const16 %at,HI16U(%imm); const16 %at,LOW16U(%imm); add %at,%at,%as; l32i %at,%at,0"},
- /* This is only PART of the loop instruction. In addition,
- hardcoded into its use is a modification of the final operand in
- the instruction in bytes 9 and 12. */
- {"loop %as,%label | %as!=1 ? IsaUseLoops",
+ /* Widening loops with literals. */
+ {"loop %as,%label | %as!=1 ? IsaUseLoops ? IsaUseL32R",
+ "loop %as,%LABEL;"
+ "rsr.lend %as;" /* LEND */
+ "wsr.lbeg %as;" /* LBEG */
+ "LITERAL %label;"
+ "l32r %as, %LITERAL;"
+ "nop;"
+ "wsr.lend %as;"
+ "isync;"
+ "rsr.lcount %as;" /* LCOUNT */
+ "addi %as, %as, 1;"
+ "LABEL"},
+ {"loopgtz %as,%label | %as!=1 ? IsaUseLoops ? IsaUseL32R",
+ "beqz %as,%label;"
+ "bltz %as,%label;"
+ "loopgtz %as,%LABEL;"
+ "rsr.lend %as;" /* LEND */
+ "wsr.lbeg %as;" /* LBEG */
+ "LITERAL %label;"
+ "l32r %as, %LITERAL;"
+ "nop;"
+ "wsr.lend %as;"
+ "isync;"
+ "rsr.lcount %as;" /* LCOUNT */
+ "addi %as, %as, 1;"
+ "LABEL"},
+ {"loopnez %as,%label | %as!=1 ? IsaUseLoops ? IsaUseL32R",
+ "beqz %as,%label;"
+ "loopnez %as,%LABEL;"
+ "rsr.lend %as;" /* LEND */
+ "wsr.lbeg %as;" /* LBEG */
+ "LITERAL %label;"
+ "l32r %as, %LITERAL;"
+ "nop;"
+ "wsr.lend %as;"
+ "isync;"
+ "rsr.lcount %as;" /* LCOUNT */
+ "addi %as, %as, 1;"
+ "LABEL"},
+
+ /* Widening loops with const16. */
+ {"loop %as,%label | %as!=1 ? IsaUseLoops ? IsaUseConst16",
"loop %as,%LABEL;"
"rsr.lend %as;" /* LEND */
"wsr.lbeg %as;" /* LBEG */
- "addi %as, %as, 0;" /* lo8(%label-%LABEL1) */
- "addmi %as, %as, 0;" /* mid8(%label-%LABEL1) */
+ "const16 %as,HI16U(%label);"
+ "const16 %as,LOW16U(%label);"
"wsr.lend %as;"
"isync;"
"rsr.lcount %as;" /* LCOUNT */
- "addi %as, %as, 1;" /* density -> addi.n %as, %as, 1 */
+ "addi %as, %as, 1;"
"LABEL"},
- {"loopgtz %as,%label | %as!=1 ? IsaUseLoops",
+ {"loopgtz %as,%label | %as!=1 ? IsaUseLoops ? IsaUseConst16",
"beqz %as,%label;"
"bltz %as,%label;"
"loopgtz %as,%LABEL;"
"rsr.lend %as;" /* LEND */
"wsr.lbeg %as;" /* LBEG */
- "addi %as, %as, 0;" /* lo8(%label-%LABEL1) */
- "addmi %as, %as, 0;" /* mid8(%label-%LABEL1) */
+ "const16 %as,HI16U(%label);"
+ "const16 %as,LOW16U(%label);"
"wsr.lend %as;"
"isync;"
"rsr.lcount %as;" /* LCOUNT */
- "addi %as, %as, 1;" /* density -> addi.n %as, %as, 1 */
+ "addi %as, %as, 1;"
"LABEL"},
- {"loopnez %as,%label | %as!=1 ? IsaUseLoops",
+ {"loopnez %as,%label | %as!=1 ? IsaUseLoops ? IsaUseConst16",
"beqz %as,%label;"
"loopnez %as,%LABEL;"
"rsr.lend %as;" /* LEND */
"wsr.lbeg %as;" /* LBEG */
- "addi %as, %as, 0;" /* lo8(%label-%LABEL1) */
- "addmi %as, %as, 0;" /* mid8(%label-%LABEL1) */
+ "const16 %as,HI16U(%label);"
+ "const16 %as,LOW16U(%label);"
"wsr.lend %as;"
"isync;"
"rsr.lcount %as;" /* LCOUNT */
- "addi %as, %as, 1;" /* density -> addi.n %as, %as, 1 */
+ "addi %as, %as, 1;"
"LABEL"},
/* Relaxing to wide branches. Order is important here. With wide
--
2.11.0
|
