search for: simplifyinstructionsinblock

LLVM has two similar bits of infrastructure: a simplifyInstructionsInBlock function and a SimplifyInstructions pass, both intended to be lightweight “fix up this code without doing serious optimizations” functions, as far as I can tell. I don’t think either is used in a performance-sensitive place in-tree; the former is mostly called in minor places when doing CFG twiddli...

> > Instead of adding the operands to a list, erase the instruction and add them to the worklist wouldn’t be probably faster something like: > > if (Instruction *Used = dyn_cast<Instruction>(*OI)) > if (Used->hasOneUse()) > WorkList.insert(Used); > > If it has one use is going to be the instruction we are going to remove anyway, right? I don’t think this

...truction? in LLVM passes don't schedule other passes. Whoever schedules your pass to run can just schedule a dead code elimination pass after yours (or instcombine, or some other pass that will zap this kind of thing). Alternatively, your pass can use a utility function to do it, for example SimplifyInstructionsInBlock, defined in llvm/Transforms/Utils/Local.h Ciao, Duncan.

My pass in LLVM generates an IR like this %5 = icmp eq i32 %4, 0 %7 = or i1 %5, %5 ;. . . Since the 'or' instruction is actually not needed(dead code), I replaced all occurences of %7 with %5. Now, the 'or' instruction should get deleted. How can I call Dead Code Elimination pass of LLVM from my pass or is there any method to remove that 'or' instruction? Thank you.

> On Sep 14, 2015, at 5:02 PM, Mehdi Amini via llvm-dev <llvm-dev at lists.llvm.org> wrote: > >> >> On Sep 14, 2015, at 2:58 PM, Pete Cooper via llvm-dev <llvm-dev at lists.llvm.org> wrote: >> >> >>> On Sep 14, 2015, at 2:49 PM, Matt Arsenault via llvm-dev <llvm-dev at lists.llvm.org> wrote: >>> >>> On 09/14/2015 02:47