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tcg/arm: Support armv4t in tcg_out_goto and tcg_out_call 

ARMv4T has BX as its only interworking instruction.  In order
to support testing of different architecture revisions with a
qemu binary that may have been built for, say ARMv6T2, fill in
the blank required to make calls to helpers in thumb mode.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-08-12 13:31:13 -10:00
parent 4ae82ca7eb
commit b87c1add03
1 changed files with 34 additions and 15 deletions

49
tcg/arm/tcg-target.c.inc
View File

@ -1211,7 +1211,8 @@ static inline void tcg_out_st8(TCGContext *s, int cond,
tcg_out_st8_12(s, cond, rd, rn, offset);
}
/* The _goto case is normally between TBs within the same code buffer, and
/*
* The _goto case is normally between TBs within the same code buffer, and
* with the code buffer limited to 16MB we wouldn't need the long case.
* But we also use it for the tail-call to the qemu_ld/st helpers, which does.
*/
@ -1219,38 +1220,56 @@ static void tcg_out_goto(TCGContext *s, int cond, const tcg_insn_unit *addr)
{
intptr_t addri = (intptr_t)addr;
ptrdiff_t disp = tcg_pcrel_diff(s, addr);
bool arm_mode = !(addri & 1);
if ((addri & 1) == 0 && disp - 8 < 0x01fffffd && disp - 8 > -0x01fffffd) {
if (arm_mode && disp - 8 < 0x01fffffd && disp - 8 > -0x01fffffd) {
tcg_out_b_imm(s, cond, disp);
return;
}
tcg_out_movi_pool(s, cond, TCG_REG_PC, addri);
/* LDR is interworking from v5t. */
if (arm_mode || use_armv5t_instructions) {
tcg_out_movi_pool(s, cond, TCG_REG_PC, addri);
return;
}
/* else v4t */
tcg_out_movi32(s, COND_AL, TCG_REG_TMP, addri);
tcg_out_bx_reg(s, COND_AL, TCG_REG_TMP);
}
/* The call case is mostly used for helpers - so it's not unreasonable
* for them to be beyond branch range */
/*
* The call case is mostly used for helpers - so it's not unreasonable
* for them to be beyond branch range.
*/
static void tcg_out_call(TCGContext *s, const tcg_insn_unit *addr)
{
intptr_t addri = (intptr_t)addr;
ptrdiff_t disp = tcg_pcrel_diff(s, addr);
bool arm_mode = !(addri & 1);
if (disp - 8 < 0x02000000 && disp - 8 >= -0x02000000) {
if (addri & 1) {
/* Use BLX if the target is in Thumb mode */
if (!use_armv5t_instructions) {
tcg_abort();
}
tcg_out_blx_imm(s, disp);
} else {
if (arm_mode) {
tcg_out_bl_imm(s, COND_AL, disp);
return;
}
} else if (use_armv7_instructions) {
if (use_armv5t_instructions) {
tcg_out_blx_imm(s, disp);
return;
}
}
if (use_armv5t_instructions) {
tcg_out_movi32(s, COND_AL, TCG_REG_TMP, addri);
tcg_out_blx_reg(s, COND_AL, TCG_REG_TMP);
} else {
} else if (arm_mode) {
/* ??? Know that movi_pool emits exactly 1 insn. */
tcg_out_dat_imm(s, COND_AL, ARITH_ADD, TCG_REG_R14, TCG_REG_PC, 0);
tcg_out_mov_reg(s, COND_AL, TCG_REG_R14, TCG_REG_PC);
tcg_out_movi_pool(s, COND_AL, TCG_REG_PC, addri);
} else {
tcg_out_movi32(s, COND_AL, TCG_REG_TMP, addri);
tcg_out_mov_reg(s, COND_AL, TCG_REG_R14, TCG_REG_PC);
tcg_out_bx_reg(s, COND_AL, TCG_REG_TMP);
}
}