Fix for PR14824: Optimization arm_ldst_opt inserts newly generated instruction vldmia at incorrect position

Stepan Dyatkovskiy stpworld at narod.ru
Wed Mar 13 03:38:03 PDT 2013


Hello Hao,

hao liu wrote:
> But I just have one question: do we need to consider about the mix
> situation of registers of S, D and Q?  I just wonder the existence of some
> code like:
>        S1 = ldr r0, #4;
>        D1 = ldr r0, #8;
>        Q1 = ldr r0, #16;
>        ...

I checked this case.
By now, it is possible to get llc emit code like this:
         ...
         vldr    s4, [r0, #400]
         vldr    d16, [r1]
         vldr    s0, [r0, #432]
         ...

I suppose there is case, where D0 is used instead of D16, and then for 
example S0 and S1 are implicitly reused.

In Jiangning's Liu attachment:
http://llvm.org/bugs/attachment.cgi?id=9821

try to insert code like this (somewhere in middle):

   %d_ptr = bitcast <8 x i64> * %source to <8 x double> *
   %doubles = getelementptr inbounds <8 x double> * %d_ptr, i32 0, i32 0
   %initial_double = load double * %doubles, align 64
   %modified_double = fadd double %initial_double, %initial_double
   store double %modified_double, double * %doubles

It would emit the mix of vldrs and vldrd instructions.

I attached modified test case. Try to run it with command:
"./llc ldst_opt_bug-q.ll -mcpu=cortex-a9 -mattr=+neon,+neonfp"

-Stepan.

-------------- next part --------------
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:64:128-a0:0:64-n32-S64"
target triple = "thumbv7-none-linux-gnueabi"

define void @sample_test(<8 x i64> * %secondSource, <8 x i64> * %source, <8 x i64> * %dest) nounwind {
entry:
  %s0 = load <8 x i64> * %source, align 64
  %s1 = load <8 x i64> * %secondSource, align 64
  %s2 = bitcast <8 x i64> %s0 to i512
  %data.i.i.48.extract.shift = lshr i512 %s2, 384
  %data.i.i.48.extract.trunc = trunc i512 %data.i.i.48.extract.shift to i64
  %arrayidx64 = getelementptr inbounds <8 x i64> * %source, i32 6
  %s120 = load <8 x i64> * %arrayidx64, align 64
  %arrayidx67 = getelementptr inbounds <8 x i64> * %secondSource, i32 6
  %s121 = load <8 x i64> * %arrayidx67, align 64
  %s122 = bitcast <8 x i64> %s120 to i512

  %d_ptr = bitcast <8 x i64> * %source to <8 x double> *
  %doubles = getelementptr inbounds <8 x double> * %d_ptr, i32 0, i32 0
  %initial_double = load double * %doubles, align 64
  %modified_double = fadd double %initial_double, %initial_double
  store double %modified_double, double * %doubles

  %data.i.i677.48.extract.shift = lshr i512 %s122, 384
  %data.i.i677.48.extract.trunc = trunc i512 %data.i.i677.48.extract.shift to i64
  %s123 = insertelement <8 x i64> undef, i64 %data.i.i677.48.extract.trunc, i32 0
  %data.i.i677.32.extract.shift = lshr i512 %s122, 256
  %data.i.i677.32.extract.trunc = trunc i512 %data.i.i677.32.extract.shift to i64
  %s124 = insertelement <8 x i64> %s123, i64 %data.i.i677.32.extract.trunc, i32 1
  %data.i.i677.16.extract.shift = lshr i512 %s122, 128
  %data.i.i677.16.extract.trunc = trunc i512 %data.i.i677.16.extract.shift to i64
  %s125 = insertelement <8 x i64> %s124, i64 %data.i.i677.16.extract.trunc, i32 2
  %data.i.i677.56.extract.shift = lshr i512 %s122, 448
  %data.i.i677.56.extract.trunc = trunc i512 %data.i.i677.56.extract.shift to i64
  %s126 = insertelement <8 x i64> %s125, i64 %data.i.i677.56.extract.trunc, i32 3
  %data.i.i677.24.extract.shift = lshr i512 %s122, 192
  %data.i.i677.24.extract.trunc = trunc i512 %data.i.i677.24.extract.shift to i64
  %s127 = insertelement <8 x i64> %s126, i64 %data.i.i677.24.extract.trunc, i32 4
  %s128 = insertelement <8 x i64> %s127, i64 %data.i.i677.32.extract.trunc, i32 5
  %s129 = insertelement <8 x i64> %s128, i64 %data.i.i677.16.extract.trunc, i32 6
  %s130 = insertelement <8 x i64> %s129, i64 %data.i.i677.56.extract.trunc, i32 7
  %s131 = bitcast <8 x i64> %s121 to i512
  %data.i1.i676.48.extract.shift = lshr i512 %s131, 384
  %data.i1.i676.48.extract.trunc = trunc i512 %data.i1.i676.48.extract.shift to i64
  %s132 = insertelement <8 x i64> undef, i64 %data.i1.i676.48.extract.trunc, i32 0
  %data.i1.i676.32.extract.shift = lshr i512 %s131, 256
  %data.i1.i676.32.extract.trunc = trunc i512 %data.i1.i676.32.extract.shift to i64
  %s133 = insertelement <8 x i64> %s132, i64 %data.i1.i676.32.extract.trunc, i32 1
  %data.i1.i676.16.extract.shift = lshr i512 %s131, 128
  %data.i1.i676.16.extract.trunc = trunc i512 %data.i1.i676.16.extract.shift to i64
  %s134 = insertelement <8 x i64> %s133, i64 %data.i1.i676.16.extract.trunc, i32 2
  %data.i1.i676.56.extract.shift = lshr i512 %s131, 448
  %data.i1.i676.56.extract.trunc = trunc i512 %data.i1.i676.56.extract.shift to i64
  %s135 = insertelement <8 x i64> %s134, i64 %data.i1.i676.56.extract.trunc, i32 3
  %data.i1.i676.24.extract.shift = lshr i512 %s131, 192
  %data.i1.i676.24.extract.trunc = trunc i512 %data.i1.i676.24.extract.shift to i64
  %s136 = insertelement <8 x i64> %s135, i64 %data.i1.i676.24.extract.trunc, i32 4
  %s137 = insertelement <8 x i64> %s136, i64 %data.i1.i676.32.extract.trunc, i32 5
  %s138 = insertelement <8 x i64> %s137, i64 %data.i1.i676.16.extract.trunc, i32 6
  %s139 = insertelement <8 x i64> %s138, i64 %data.i1.i676.56.extract.trunc, i32 7
  %vecinit28.i.i699 = shufflevector <8 x i64> %s139, <8 x i64> %s130, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 12, i32 undef, i32 undef, i32 undef>
  %vecinit35.i.i700 = shufflevector <8 x i64> %vecinit28.i.i699, <8 x i64> %s139, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 13, i32 undef, i32 undef>
  %vecinit42.i.i701 = shufflevector <8 x i64> %vecinit35.i.i700, <8 x i64> %s139, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 14, i32 undef>
  %vecinit49.i.i702 = shufflevector <8 x i64> %vecinit42.i.i701, <8 x i64> %s130, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 15>
  %arrayidx72 = getelementptr inbounds <8 x i64> * %dest, i32 6
  store <8 x i64> %vecinit49.i.i702, <8 x i64> * %arrayidx72, align 64
  %arrayidx75 = getelementptr inbounds <8 x i64> * %source, i32 7
  %s140 = load <8 x i64> * %arrayidx75, align 64
  %arrayidx78 = getelementptr inbounds <8 x i64> * %secondSource, i32 7
  %s141 = load <8 x i64> * %arrayidx78, align 64
  %s142 = bitcast <8 x i64> %s140 to i512
  %data.i.i650.32.extract.shift = lshr i512 %s142, 256
  %data.i.i650.32.extract.trunc = trunc i512 %data.i.i650.32.extract.shift to i64
  %s143 = insertelement <8 x i64> undef, i64 %data.i.i650.32.extract.trunc, i32 0
  %s144 = insertelement <8 x i64> %s143, i64 %data.i.i650.32.extract.trunc, i32 1
  %data.i.i650.16.extract.shift = lshr i512 %s142, 128
  %data.i.i650.16.extract.trunc = trunc i512 %data.i.i650.16.extract.shift to i64
  %s145 = insertelement <8 x i64> %s144, i64 %data.i.i650.16.extract.trunc, i32 2
  %data.i.i650.8.extract.shift = lshr i512 %s142, 64
  %data.i.i650.8.extract.trunc = trunc i512 %data.i.i650.8.extract.shift to i64
  %s146 = insertelement <8 x i64> %s145, i64 %data.i.i650.8.extract.trunc, i32 3
  %s147 = insertelement <8 x i64> %s146, i64 %data.i.i650.8.extract.trunc, i32 4
  %data.i.i650.48.extract.shift = lshr i512 %s142, 384
  %data.i.i650.48.extract.trunc = trunc i512 %data.i.i650.48.extract.shift to i64
  %s148 = insertelement <8 x i64> %s147, i64 %data.i.i650.48.extract.trunc, i32 5
  %s149 = insertelement <8 x i64> %s148, i64 %data.i.i650.16.extract.trunc, i32 6
  %data.i.i650.0.extract.trunc = trunc i512 %s142 to i64
  %s150 = insertelement <8 x i64> %s149, i64 %data.i.i650.0.extract.trunc, i32 7
  %s151 = bitcast <8 x i64> %s141 to i512
  %data.i1.i649.32.extract.shift = lshr i512 %s151, 256
  %data.i1.i649.32.extract.trunc = trunc i512 %data.i1.i649.32.extract.shift to i64
  %s152 = insertelement <8 x i64> undef, i64 %data.i1.i649.32.extract.trunc, i32 0
  %s153 = insertelement <8 x i64> %s152, i64 %data.i1.i649.32.extract.trunc, i32 1
  %data.i1.i649.16.extract.shift = lshr i512 %s151, 128
  %data.i1.i649.16.extract.trunc = trunc i512 %data.i1.i649.16.extract.shift to i64
  %s154 = insertelement <8 x i64> %s153, i64 %data.i1.i649.16.extract.trunc, i32 2
  %data.i1.i649.8.extract.shift = lshr i512 %s151, 64
  %data.i1.i649.8.extract.trunc = trunc i512 %data.i1.i649.8.extract.shift to i64
  %s155 = insertelement <8 x i64> %s154, i64 %data.i1.i649.8.extract.trunc, i32 3
  %s156 = insertelement <8 x i64> %s155, i64 %data.i1.i649.8.extract.trunc, i32 4
  %data.i1.i649.48.extract.shift = lshr i512 %s151, 384
  %data.i1.i649.48.extract.trunc = trunc i512 %data.i1.i649.48.extract.shift to i64
  %s157 = insertelement <8 x i64> %s156, i64 %data.i1.i649.48.extract.trunc, i32 5
  %s158 = insertelement <8 x i64> %s157, i64 %data.i1.i649.16.extract.trunc, i32 6
  %data.i1.i649.0.extract.trunc = trunc i512 %s151 to i64
  %s159 = insertelement <8 x i64> %s158, i64 %data.i1.i649.0.extract.trunc, i32 7
  %vecinit7.i.i669 = shufflevector <8 x i64> %s159, <8 x i64> %s150, <8 x i32> <i32 0, i32 9, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef>
  %vecinit14.i.i670 = shufflevector <8 x i64> %vecinit7.i.i669, <8 x i64> %s150, <8 x i32> <i32 0, i32 1, i32 10, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef>
  %vecinit21.i.i671 = shufflevector <8 x i64> %vecinit14.i.i670, <8 x i64> %s150, <8 x i32> <i32 0, i32 1, i32 2, i32 11, i32 undef, i32 undef, i32 undef, i32 undef>
  %vecinit28.i.i672 = shufflevector <8 x i64> %vecinit21.i.i671, <8 x i64> %s150, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 12, i32 undef, i32 undef, i32 undef>
  %vecinit35.i.i673 = shufflevector <8 x i64> %vecinit28.i.i672, <8 x i64> %s159, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 13, i32 undef, i32 undef>
  %vecinit42.i.i674 = shufflevector <8 x i64> %vecinit35.i.i673, <8 x i64> %s159, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 14, i32 undef>
  %vecinit49.i.i675 = shufflevector <8 x i64> %vecinit42.i.i674, <8 x i64> %s159, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 15>
  %arrayidx83 = getelementptr inbounds <8 x i64> * %dest, i32 7
  store <8 x i64> %vecinit49.i.i675, <8 x i64> * %arrayidx83, align 64
  ret void
}


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