[llvm-dev] Handling floating point exceptions in RISC-V using compiler

[faisal via llvm-dev]

Hi,

I am interested in handling floating point exceptions for a RISC-V 
hardware.RISC-V ISA does not mandate generating interrupts when any 
floating point exception occurs. Only corresponding bit in floating 
point control and status register is set when any floating point 
exception occurs.

So, i want compiler to add checks for floating point exceptions.

I think this requires changing how a compiler performs some basic 
operations.

After every operation which may lead to floating point exceptions like 
addition and multiplication,  status bits in FPCSR register should be 
checked and branching should occur if any of the bits is set.

I plan to make these changes in llvm for RISC-V and then do the same for 
gcc for RISC-V. This most likely will result in making things slow( 
significantly ) as number of assembly instructions will increase.

I guess that changes has to be made in the code responsible for 
generating assembly from RTL. It would be very helpful if i can get some 
hints on how should i proceed.

Faisal Riyaz