[LLVMbugs] [Bug 19935] New: arm926ej-s: Assertion `ARM::GPRRegClass.contains(DestReg, SrcReg) && "Thumb1 can only copy GPR registers"'

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=19935

            Bug ID: 19935
           Summary: arm926ej-s: Assertion
                    `ARM::GPRRegClass.contains(DestReg, SrcReg) && "Thumb1
                    can only copy GPR registers"'
           Product: new-bugs
           Version: trunk
          Hardware: Other
                OS: other
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: sgundapa at codeaurora.org
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Created attachment 12599
  --> http://llvm.org/bugs/attachment.cgi?id=12599&action=edit
A bugpoint reduced test case

Hi,
   I have been seeing an assertion up until very recently on my arm926 target.
I have attached a bug point reduced test case for your reference.
You can see the assertion with the below command
$ llc bugpoint-reduced-simplified.ll -mcpu=arm926ej-s -mattr=+vfp2

I run my benchmarks usually with 
clang  -mfloat-abi=softfp -mfpu=vfp -mcpu=arm926ej-s -O2 -mthumb -c /tmp/test.c

The assertion is observed on thumb mode only. The arm mode seem fine.

I used git bisect to triage the issue and figured out the following commit is
the cause.

commit e2948385b92b5aec6ac5187ca4fee367db2f0dd1
Author: Oliver Stannard <oliver.stannard at arm.com>
Date:   Fri May 9 14:01:47 2014 +0000

    ARM: HFAs must be passed in consecutive registers

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