[LLVMdev] Error when cond of select instruction is a vector

[Rotem, Nadav]

I fixed this bug in r142488. You can give it a try.

Cheers,
Nadav

From: Fan Dawei [mailto:fandawei.s at gmail.com]
Sent: Wednesday, October 19, 2011 11:06
To: Rotem, Nadav
Cc: LLVMdev at cs.uiuc.edu
Subject: Re: [LLVMdev] Error when cond of select instruction is a vector

Hi Rotem,

What do you mean by "you can use the <4 x float> type for which the vselect works".

Do you mean that then back-end can correctly split the operands when it is a four elements vector? I've try that, but it still fails.
On Wed, Oct 19, 2011 at 4:21 PM, Rotem, Nadav <nadav.rotem at intel.com<mailto:nadav.rotem at intel.com>> wrote:
This is indeed a bug. I get a different error on my machine. Until we solve this bug, as a workaround, you can use the <4 x float> type for which the vselect works.


From: llvmdev-bounces at cs.uiuc.edu<mailto:llvmdev-bounces at cs.uiuc.edu> [mailto:llvmdev-bounces at cs.uiuc.edu<mailto:llvmdev-bounces at cs.uiuc.edu>] On Behalf Of Fan Dawei
Sent: Wednesday, October 19, 2011 10:10
To: LLVMdev at cs.uiuc.edu<mailto:LLVMdev at cs.uiuc.edu>
Subject: [LLVMdev] Error when cond of select instruction is a vector

Hi LLVMdev,

In the specification of llvm ir, the select operation can takes a condition of vector type,
'select' Instruction
Syntax:

  <result> = select selty <cond>, <ty> <val1>, <ty> <val2>             ; yields ty



  selty is either i1 or {<N x i1>}

Overview:

The 'select' instruction is used to choose one value based on a condition, without branching.

If the condition is a vector of i1, then the value arguments must be vectors of the same size, and the selection is done element by element.

However when I create a program use vector of il as the type of condition. The back-end fails and complains:

SplitVectorOperand Op #0: 0x2b75370: f32 = select 0x2b6c800, 0x2b75270, 0x2b75170 [ID=0]

Do not know how to split this operator's operand!

The following program is a valid IR which passed by the checker. However the back-end fails on all the targets I've tested, including x86, mips and sparc. Is it a target independent bug?

 define void @main() {
entry:
  %Cy300 = alloca <4 x float>
  %Cy11a = alloca <2 x float>
  %Cy118 = alloca <2 x float>
  %Cy119 = alloca <2 x float>
  br label %B1

B1:                                               ; preds = %entry
  %0 = load <2 x float>* %Cy119
  %1 = fptosi <2 x float> %0 to <2 x i32>
  %2 = sitofp <2 x i32> %1 to <2 x float>
  %3 = fcmp ogt <2 x float> %0, zeroinitializer
  %4 = fadd <2 x float> %2, <float 1.000000e+00, float 1.000000e+00>
  %5 = select <2 x i1> %3, <2 x float> %4, <2 x float> %2
  %6 = fcmp oeq <2 x float> %2, %0
  %7 = select <2 x i1> %6, <2 x float> %0, <2 x float> %5
  store <2 x float> %7, <2 x float>* %Cy118
  %8 = load <2 x float>* %Cy118
  store <2 x float> %8, <2 x float>* %Cy11a
  ret void
}


Thanks,
David
---------------------------------------------------------------------
Intel Israel (74) Limited

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.

---------------------------------------------------------------------
Intel Israel (74) Limited

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20111019/47c4daad/attachment.html>