search for: cantrap

See https://reviews.llvm.org/D63036 for the full patch and description. Essentially, the Constant::canTrap API is going away. To make this work, the semantics of division and remainder constant expressions are changing slightly, so division by zero produces poison, not undefined behavior. (The corresponding instructions still have undefined behavior.) This change should make writing and understanding...

...3A__reviews.llvm.org_D63036&d=DwMFaQ&c=slrrB7dE8n7gBJbeO0g-IQ&r=O_4M49EtSpZ_-BQYeigzGv0P4__noMcSu2RYEjS1vKs&m=HPH8LbjOYmP3G9p6HJYKLtOFGQQJ0aWeEc7QU46PkOw&s=Q-PK-STEJTkFgcTQeOjIR7RY4e_iIHz191Qk_8syQlA&e=> > for the full patch and description. Essentially, the Constant::canTrap > API is going away. To make this work, the semantics of division and > remainder constant expressions are changing slightly, so division by zero > produces poison, not undefined behavior. (The corresponding instructions > still have undefined behavior.) This change should make writi...

...reviews.llvm.org_D63036&d=DwMFaQ&c=slrrB7dE8n7gBJbeO0g-IQ&r=O_4M49EtSpZ_-BQYeigzGv0P4__noMcSu2RYEjS1vKs&m=HPH8LbjOYmP3G9p6HJYKLtOFGQQJ0aWeEc7QU46PkOw&s=Q-PK-STEJTkFgcTQeOjIR7RY4e_iIHz191Qk_8syQlA&e=> >> for the full patch and description. Essentially, the Constant::canTrap >> API is going away. To make this work, the semantics of division and >> remainder constant expressions are changing slightly, so division by zero >> produces poison, not undefined behavior. (The corresponding instructions >> still have undefined behavior.) This change s...

That's an interesting idea. What are the essential differences between the new subclass and ConstantExpr? Will it end up like ConstantExpr? Or you want it to be ConstantExpr 'done right'? Thanks. Yuan -----Original Message----- From: Eli Friedman [mailto:eli.friedman at gmail.com] Sent: Monday, December 17, 2012 5:40 PM To: Yuan Lin Cc: Chris Lattner; llvmdev at cs.uiuc.edu

Hi Sanjay, Thanks, I saw this flag and it's definitely should be considered, but it appeared to me to be static characteristic of target platform. I'm not sure how appropriate it would be to change its value from a front-end. It says "Has", while optional flag would rather say "Uses" meaning that implementation cares about floating point exceptions. Regards, Sergey

...rms/Utils/SimplifyCFG.cpp @@ -267,7 +267,7 @@ static bool DominatesMergePoint(Value *V, BasicBlock *BB, // Non-instructions all dominate instructions, but not all constantexprs // can be executed unconditionally. if (ConstantExpr *C = dyn_cast<ConstantExpr>(V)) - if (C->canTrap()) + if (C->canTrap() || !isSafeToSpeculativelyExecute(V, DL)) return false; return true; } -- 1.8.4 -------------- next part -------------- Subject: [PATCH 3/7] Add HonorFPExceptions flag to TargetOptions --- include/llvm/Target/TargetOptions.h | 7 ++++++- 1 file chan...

On Wed, Mar 25, 2020 at 8:52 AM Doerfert, Johannes <jdoerfert at anl.gov> wrote: > I think the solution space for the value/use-list issue might be larger > than what was mentioned so far. > > > Some random thoughts: > > If no pass ever walks the use list of a constant, except globals which > we could handle differently, we could get rid of their use-list or >