Displaying 4 results from an estimated 4 matches for "predicateinstruct".
2017 Mar 07
2
Specifying conditional blocks for the back end
...in ISelLowering from the VSELECT LLVM
instruction, and these bad transformations happen even before scheduling, at later I-sel
subpasses, I try to fix this problem by lowering VSELECT to only one pseudo-instruction
and LATER translate it to a list of instructions and use bundles and maybe also
PredicateInstruction(), which is employed also in IfConversion.cpp.
More exactly I'm trying to use a pseudo-instruction that will get translated to a
sequence of 4 MachineInstr, namely:
// These 4 instructions replace the pseudo-instruction I use for LLVM's VSELECT
R31 = OR srcVselect...
2017 Mar 03
2
Specifying conditional blocks for the back end
Hello.
For my back end for the Connex SIMD research processor I want to implement
conditional blocks (I guess the better term is predicated blocks). Predicated blocks are
bordered by two instructions WHEREEQ (or WHERELT, etc) and ENDWHERE.
For example, the following code executes the instructions inside the WHERE block only
for the lanes where R0 == R1:
EQ R0, R1;
2016 Mar 29
0
IfConversion and representation of predicates
...pass may only run after register allocation?
I often encounter this bad scenario, and I think it could be entirely avoided if IfConversion ran before register allocation: the block-to-be-predicated contains load-immediate (LI) instructions. The LI instructions accept any 32-bit immediate. TII:PredicateInstruction can transform LI into a conditional-select (CSELxx) instruction, but on my target, CSELxx only accepts a 16-bit immediate. This is less general; not all LI instructions can be predicated into CSELxx instructions, thus frequently preventing the block predication transformation . I don't thi...
2011 Nov 02
0
[LLVMdev] ifconversion following br_cc instructions
Hi,
I am trying to implement support for an if-conversion pass in a backend for the ADRES CGRA architecture.
>From studying the existing IfConversion pass, I observed the following:
- The PredicateInstruction method is meant to insert guards into conditional instructions.
- This method assumes that one will be able to get the predicate from the conditional branch instruction
on which the conditional instruction depends.
- So implicitly, this method assumes that the conditional branch instructio...