"Register class of operand and regclass of use don't agree!" on x86 glibc atan

[llvmbot]

Bugzilla Link	1211
Resolution	DUPLICATE
Resolved on	Feb 22, 2010 12:51
Version	unspecified
OS	Linux
Reporter	LLVM Bugzilla Contributor

Extended Description

The following is simplified from the x86 atan2 code in glibc's mathinline.h:

double atan (double x)
{
register double value;
__asm ("fld1; fpatan" : "=t" (value) : "0" (x) : "st(1)");
return value;
}

A quite recent llvm-gcc4 barfs on it:

$ gcc -c atan.c
cc1: llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp:364: void
llvm::ScheduleDAG::AddOperand(llvm::MachineInstr*, llvm::SDOperand, unsigned
int, const llvm::TargetInstrDescriptor*, llvm::DenseMap<llvm::SDNode*,
unsigned int>&): Assertion `RegMap->getRegClass(VReg) == RC && "Register class
of operand and regclass of use don't agree!"' failed.
atan.c:6: internal compiler error: Aborted
Please submit a full bug report,
with preprocessed source if appropriate.
See URL:http://llvm.org/bugs for instructions.

[lattner]

Yep, we don't support the X87 FP stack yet. There should be a -D option you can build with to avoid these
asms (-DNO_MATH_INLINES ?)

-Chris

*** This bug has been marked as a duplicate of 879 ***

[lattner]

mentioned in issue #1251