diff options
Diffstat (limited to 'gcc/config/arm/arm.c')
| -rw-r--r-- | gcc/config/arm/arm.c | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index 2c62c518e67..3ad4c752ac8 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -25933,4 +25933,256 @@ arm_autoinc_modes_ok_p (enum machine_mode mode, enum arm_auto_incmodes code) return false; } +/* The default expansion of general 64-bit shifts in core-regs is suboptimal, + on ARM, since we know that shifts by negative amounts are no-ops. + Additionally, the default expansion code is not available or suitable + for post-reload insn splits (this can occur when the register allocator + chooses not to do a shift in NEON). + + This function is used in both initial expand and post-reload splits, and + handles all kinds of 64-bit shifts. + + Input requirements: + - It is safe for the input and output to be the same register, but + early-clobber rules apply for the shift amount and scratch registers. + - Shift by register requires both scratch registers. Shift by a constant + less than 32 in Thumb2 mode requires SCRATCH1 only. In all other cases + the scratch registers may be NULL. + - Ashiftrt by a register also clobbers the CC register. */ +void +arm_emit_coreregs_64bit_shift (enum rtx_code code, rtx out, rtx in, + rtx amount, rtx scratch1, rtx scratch2) +{ + rtx out_high = gen_highpart (SImode, out); + rtx out_low = gen_lowpart (SImode, out); + rtx in_high = gen_highpart (SImode, in); + rtx in_low = gen_lowpart (SImode, in); + + /* Terminology: + in = the register pair containing the input value. + out = the destination register pair. + up = the high- or low-part of each pair. + down = the opposite part to "up". + In a shift, we can consider bits to shift from "up"-stream to + "down"-stream, so in a left-shift "up" is the low-part and "down" + is the high-part of each register pair. */ + + rtx out_up = code == ASHIFT ? out_low : out_high; + rtx out_down = code == ASHIFT ? out_high : out_low; + rtx in_up = code == ASHIFT ? in_low : in_high; + rtx in_down = code == ASHIFT ? in_high : in_low; + + gcc_assert (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT); + gcc_assert (out + && (REG_P (out) || GET_CODE (out) == SUBREG) + && GET_MODE (out) == DImode); + gcc_assert (in + && (REG_P (in) || GET_CODE (in) == SUBREG) + && GET_MODE (in) == DImode); + gcc_assert (amount + && (((REG_P (amount) || GET_CODE (amount) == SUBREG) + && GET_MODE (amount) == SImode) + || CONST_INT_P (amount))); + gcc_assert (scratch1 == NULL + || (GET_CODE (scratch1) == SCRATCH) + || (GET_MODE (scratch1) == SImode + && REG_P (scratch1))); + gcc_assert (scratch2 == NULL + || (GET_CODE (scratch2) == SCRATCH) + || (GET_MODE (scratch2) == SImode + && REG_P (scratch2))); + gcc_assert (!REG_P (out) || !REG_P (amount) + || !HARD_REGISTER_P (out) + || (REGNO (out) != REGNO (amount) + && REGNO (out) + 1 != REGNO (amount))); + + /* Macros to make following code more readable. */ + #define SUB_32(DEST,SRC) \ + gen_addsi3 ((DEST), (SRC), gen_rtx_CONST_INT (VOIDmode, -32)) + #define RSB_32(DEST,SRC) \ + gen_subsi3 ((DEST), gen_rtx_CONST_INT (VOIDmode, 32), (SRC)) + #define SUB_S_32(DEST,SRC) \ + gen_addsi3_compare0 ((DEST), (SRC), \ + gen_rtx_CONST_INT (VOIDmode, -32)) + #define SET(DEST,SRC) \ + gen_rtx_SET (SImode, (DEST), (SRC)) + #define SHIFT(CODE,SRC,AMOUNT) \ + gen_rtx_fmt_ee ((CODE), SImode, (SRC), (AMOUNT)) + #define LSHIFT(CODE,SRC,AMOUNT) \ + gen_rtx_fmt_ee ((CODE) == ASHIFT ? ASHIFT : LSHIFTRT, \ + SImode, (SRC), (AMOUNT)) + #define REV_LSHIFT(CODE,SRC,AMOUNT) \ + gen_rtx_fmt_ee ((CODE) == ASHIFT ? LSHIFTRT : ASHIFT, \ + SImode, (SRC), (AMOUNT)) + #define ORR(A,B) \ + gen_rtx_IOR (SImode, (A), (B)) + #define BRANCH(COND,LABEL) \ + gen_arm_cond_branch ((LABEL), \ + gen_rtx_ ## COND (CCmode, cc_reg, \ + const0_rtx), \ + cc_reg) + + /* Shifts by register and shifts by constant are handled separately. */ + if (CONST_INT_P (amount)) + { + /* We have a shift-by-constant. */ + + /* First, handle out-of-range shift amounts. + In both cases we try to match the result an ARM instruction in a + shift-by-register would give. This helps reduce execution + differences between optimization levels, but it won't stop other + parts of the compiler doing different things. This is "undefined + behaviour, in any case. */ + if (INTVAL (amount) <= 0) + emit_insn (gen_movdi (out, in)); + else if (INTVAL (amount) >= 64) + { + if (code == ASHIFTRT) + { + rtx const31_rtx = gen_rtx_CONST_INT (VOIDmode, 31); + emit_insn (SET (out_down, SHIFT (code, in_up, const31_rtx))); + emit_insn (SET (out_up, SHIFT (code, in_up, const31_rtx))); + } + else + emit_insn (gen_movdi (out, const0_rtx)); + } + + /* Now handle valid shifts. */ + else if (INTVAL (amount) < 32) + { + /* Shifts by a constant less than 32. */ + rtx reverse_amount = gen_rtx_CONST_INT (VOIDmode, + 32 - INTVAL (amount)); + + emit_insn (SET (out_down, LSHIFT (code, in_down, amount))); + emit_insn (SET (out_down, + ORR (REV_LSHIFT (code, in_up, reverse_amount), + out_down))); + emit_insn (SET (out_up, SHIFT (code, in_up, amount))); + } + else + { + /* Shifts by a constant greater than 31. */ + rtx adj_amount = gen_rtx_CONST_INT (VOIDmode, INTVAL (amount) - 32); + + emit_insn (SET (out_down, SHIFT (code, in_up, adj_amount))); + if (code == ASHIFTRT) + emit_insn (gen_ashrsi3 (out_up, in_up, + gen_rtx_CONST_INT (VOIDmode, 31))); + else + emit_insn (SET (out_up, const0_rtx)); + } + } + else + { + /* We have a shift-by-register. */ + rtx cc_reg = gen_rtx_REG (CC_NOOVmode, CC_REGNUM); + + /* This alternative requires the scratch registers. */ + gcc_assert (scratch1 && REG_P (scratch1)); + gcc_assert (scratch2 && REG_P (scratch2)); + + /* We will need the values "amount-32" and "32-amount" later. + Swapping them around now allows the later code to be more general. */ + switch (code) + { + case ASHIFT: + emit_insn (SUB_32 (scratch1, amount)); + emit_insn (RSB_32 (scratch2, amount)); + break; + case ASHIFTRT: + emit_insn (RSB_32 (scratch1, amount)); + /* Also set CC = amount > 32. */ + emit_insn (SUB_S_32 (scratch2, amount)); + break; + case LSHIFTRT: + emit_insn (RSB_32 (scratch1, amount)); + emit_insn (SUB_32 (scratch2, amount)); + break; + default: + gcc_unreachable (); + } + + /* Emit code like this: + + arithmetic-left: + out_down = in_down << amount; + out_down = (in_up << (amount - 32)) | out_down; + out_down = ((unsigned)in_up >> (32 - amount)) | out_down; + out_up = in_up << amount; + + arithmetic-right: + out_down = in_down >> amount; + out_down = (in_up << (32 - amount)) | out_down; + if (amount < 32) + out_down = ((signed)in_up >> (amount - 32)) | out_down; + out_up = in_up << amount; + + logical-right: + out_down = in_down >> amount; + out_down = (in_up << (32 - amount)) | out_down; + if (amount < 32) + out_down = ((unsigned)in_up >> (amount - 32)) | out_down; + out_up = in_up << amount; + + The ARM and Thumb2 variants are the same but implemented slightly + differently. If this were only called during expand we could just + use the Thumb2 case and let combine do the right thing, but this + can also be called from post-reload splitters. */ + + emit_insn (SET (out_down, LSHIFT (code, in_down, amount))); + + if (!TARGET_THUMB2) + { + /* Emit code for ARM mode. */ + emit_insn (SET (out_down, + ORR (SHIFT (ASHIFT, in_up, scratch1), out_down))); + if (code == ASHIFTRT) + { + rtx done_label = gen_label_rtx (); + emit_jump_insn (BRANCH (LT, done_label)); + emit_insn (SET (out_down, ORR (SHIFT (ASHIFTRT, in_up, scratch2), + out_down))); + emit_label (done_label); + } + else + emit_insn (SET (out_down, ORR (SHIFT (LSHIFTRT, in_up, scratch2), + out_down))); + } + else + { + /* Emit code for Thumb2 mode. + Thumb2 can't do shift and or in one insn. */ + emit_insn (SET (scratch1, SHIFT (ASHIFT, in_up, scratch1))); + emit_insn (gen_iorsi3 (out_down, out_down, scratch1)); + + if (code == ASHIFTRT) + { + rtx done_label = gen_label_rtx (); + emit_jump_insn (BRANCH (LT, done_label)); + emit_insn (SET (scratch2, SHIFT (ASHIFTRT, in_up, scratch2))); + emit_insn (SET (out_down, ORR (out_down, scratch2))); + emit_label (done_label); + } + else + { + emit_insn (SET (scratch2, SHIFT (LSHIFTRT, in_up, scratch2))); + emit_insn (gen_iorsi3 (out_down, out_down, scratch2)); + } + } + + emit_insn (SET (out_up, SHIFT (code, in_up, amount))); + } + + #undef SUB_32 + #undef RSB_32 + #undef SUB_S_32 + #undef SET + #undef SHIFT + #undef LSHIFT + #undef REV_LSHIFT + #undef ORR + #undef BRANCH +} + #include "gt-arm.h" |