| Message ID | 1550824961-75218-1-git-send-email-kito@andestech.com |
|---|---|
| State | New |
| Headers | show |
| Series | [NDS32] Fix nds32_split_ashiftdi3 with large shift amount | expand |
Hi Kito, Thanks for the patch. Kito Cheng <kito@andestech.com> 於 2019年2月22日 週五 下午4:42寫道： > From: Kito Cheng <kito.cheng@gmail.com> > > ChangeLog: > gcc/ > * config/nds32/nds32-md-auxiliary.c (nds32_split_ashiftdi3): > Fix wrong code gen with large shift amount. > --- > gcc/config/nds32/nds32-md-auxiliary.c | 21 ++++++++++++++------- > 1 file changed, 14 insertions(+), 7 deletions(-) > > diff --git a/gcc/config/nds32/nds32-md-auxiliary.c > b/gcc/config/nds32/nds32-md-auxiliary.c > index 33844be..71fa421 100644 > --- a/gcc/config/nds32/nds32-md-auxiliary.c > +++ b/gcc/config/nds32/nds32-md-auxiliary.c > @@ -3304,15 +3304,22 @@ nds32_split_ashiftdi3 (rtx dst, rtx src, rtx > shiftamount) > ext_start = gen_reg_rtx (SImode); > > /* > - if (shiftamount < 32) > + # In fact, we want to check shift amonut is great than or equal > 32, > + # but in some corner case, the shift amount might be very large > value, > + # however we've defined SHIFT_COUNT_TRUNCATED, so GCC think we've > + # handle that correctly without any truncate. > The comments seem that defining SHIFT_COUNT_TRUNCATED will trigger the issue. But if we define SHIFT_COUNT_TRUNCATED as 0, the issue still occurs, right? + # so check the the condition of (shiftamount & 32) is most > + # safe way to do. > + if (shiftamount & 32) > + dst_low_part = 0 > + dst_high_part = src_low_part << shiftamount & 0x1f > shiftamount & 0x1f probably could remove because nds32 sll will read low 5-bits as the shift amount. + else > dst_low_part = src_low_part << shiftamout > dst_high_part = wext (src, 32 - shiftamount) > # wext can't handle wext (src, 32) since it's only take rb[0:4] > # for extract. > dst_high_part = shiftamount == 0 ? src_high_part : dst_high_part > - else > - dst_low_part = 0 > - dst_high_part = src_low_part << shiftamount & 0x1f > + > */ > > emit_insn (gen_subsi3 (ext_start, > @@ -3331,11 +3338,11 @@ nds32_split_ashiftdi3 (rtx dst, rtx src, rtx > shiftamount) > emit_insn (gen_ashlsi3 (dst_high_part_g32, src_low_part, > new_shift_amout)); > > - emit_insn (gen_slt_compare (select_reg, shiftamount, GEN_INT (32))); > + emit_insn (gen_andsi3 (select_reg, shiftamount, GEN_INT (32))); > > - emit_insn (gen_cmovnsi (dst_low_part, select_reg, > + emit_insn (gen_cmovzsi (dst_low_part, select_reg, > dst_low_part_l32, dst_low_part_g32)); > - emit_insn (gen_cmovnsi (dst_high_part, select_reg, > + emit_insn (gen_cmovzsi (dst_high_part, select_reg, > dst_high_part_l32, dst_high_part_g32)); > } > } > Could you add a test case to illustrate the codgen changed by the patch? Thanks, Shiva
diff --git a/gcc/config/nds32/nds32-md-auxiliary.c b/gcc/config/nds32/nds32-md-auxiliary.c index 33844be..71fa421 100644 --- a/gcc/config/nds32/nds32-md-auxiliary.c +++ b/gcc/config/nds32/nds32-md-auxiliary.c @@ -3304,15 +3304,22 @@ nds32_split_ashiftdi3 (rtx dst, rtx src, rtx shiftamount) ext_start = gen_reg_rtx (SImode); /* - if (shiftamount < 32) + # In fact, we want to check shift amonut is great than or equal 32, + # but in some corner case, the shift amount might be very large value, + # however we've defined SHIFT_COUNT_TRUNCATED, so GCC think we've + # handle that correctly without any truncate. + # so check the the condition of (shiftamount & 32) is most + # safe way to do. + if (shiftamount & 32) + dst_low_part = 0 + dst_high_part = src_low_part << shiftamount & 0x1f + else dst_low_part = src_low_part << shiftamout dst_high_part = wext (src, 32 - shiftamount) # wext can't handle wext (src, 32) since it's only take rb[0:4] # for extract. dst_high_part = shiftamount == 0 ? src_high_part : dst_high_part - else - dst_low_part = 0 - dst_high_part = src_low_part << shiftamount & 0x1f + */ emit_insn (gen_subsi3 (ext_start, @@ -3331,11 +3338,11 @@ nds32_split_ashiftdi3 (rtx dst, rtx src, rtx shiftamount) emit_insn (gen_ashlsi3 (dst_high_part_g32, src_low_part, new_shift_amout)); - emit_insn (gen_slt_compare (select_reg, shiftamount, GEN_INT (32))); + emit_insn (gen_andsi3 (select_reg, shiftamount, GEN_INT (32))); - emit_insn (gen_cmovnsi (dst_low_part, select_reg, + emit_insn (gen_cmovzsi (dst_low_part, select_reg, dst_low_part_l32, dst_low_part_g32)); - emit_insn (gen_cmovnsi (dst_high_part, select_reg, + emit_insn (gen_cmovzsi (dst_high_part, select_reg, dst_high_part_l32, dst_high_part_g32)); } }
From: Kito Cheng <kito.cheng@gmail.com> ChangeLog: gcc/ * config/nds32/nds32-md-auxiliary.c (nds32_split_ashiftdi3): Fix wrong code gen with large shift amount. --- gcc/config/nds32/nds32-md-auxiliary.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)