search for: guarded

..._edge, %entry br label %for.end for.end: ; preds = %for.cond.cleanup ret void However, for loops that can be proven to execute at least once, there is no guard. This creates complications for several loop optimizations because they need to handle both guarded loops and non-guarded loops. For example, the current loop fusion pass needs to check whether two loops are control flow equivalent before fusing them (i.e., if the first loop executes, the second loop is guaranteed to execute). This is currently done by checking that the preheader of the first loo...

...cs of this intrinsic, and keep an eye on all new passes to make sure they can use it. I have a proposal how it can be done relatively easily and with minimum overhead. Let us inline the guard according to the specification: %guard_cond = and i1 %cond, %undef br i1 %guard_cond, label %guarded, label %deopt guarded: <do some useful stuff> deopt: <deoptimize and leave the compiled code> Let's notice two important facts: 1. In guarded block, %cond is true because it is implied by %guard_cond being true. 2. In deopt block, we cannot assum...

...l new passes to make sure they can use it. > > > > I have a proposal how it can be done relatively easily and with minimum overhead. Let us inline the guard according to the specification: > > > > %guard_cond = and i1 %cond, %undef > > br i1 %guard_cond, label %guarded, label %deopt > > > > guarded: > > <do some useful stuff> > > > > deopt: > > <deoptimize and leave the compiled code> > > > > Let's notice two important facts: > > 1. In guarded block, %cond is true because it i...

On Hexagon, unguarded loops cannot be converted to hardware loops. If the loop's latch branch alone handles the iteration count, including the possibility of 0, then the loop cannot be converted to a hardware loop, because hardware loops must iterate at least once. If the entire loop is guarded against zero iterat...

All, TLDR: guards currently require reasoning about implicit control flow.  LLVM struggles with implicit control flow within a basic block.  We should redesign guards to admit this rather than trying to boil the ocean. As you may be aware, LLVM currently has experimental support for a construct called a "guard".  A guard is like a branch to a potential deoptimzation point, except

Replies inline. At a high level, it feels like we'll eventually need a new instruction to represent the kind of control flow a guard entails (to be clear: we should probably still start with an intrinsic) -- they are fairly well-behaved, i.e. readonly, nounwind etc. as far as the immediate "physical" caller is concerned, but not so as far as its callers's callers are concerned.

Hi all, Guard intrinsics[0] are similar in nature to Assume intrinsics, in that the condition passed to a guard intrinsic call is known to be true at locations dominated (but *not* post-dominated) by the call[1]. I'd like to re-use the AssumptionCache infrastructure that already exists to teach the mid level optimizer to exploit this property. The steps I want to take are (not necessarily

R 2.1.0/src/include from 2005/04/18 download Naming inconsistent for guards as well but that's pedantic. Simple convention: file <foo.h> #ifndef R_FOO_H file <R_ext/bar.h> #ifndef R_EXT_BAR_H Missing guards: <IOStuff.h> <Internal.h> <Parse.h> <R_ext/GraphicsBase.h> <R_ext/GraphicsDevice.h> <R_ext/GraphicsEngine.h>

This is a proposal to add guard intrinsics to LLVM. Couple of glossary items: when I say "interpreter" I mean "the most conservative tier in the compilation stack" which can be an actual interpreter, a "splat compiler" or even a regular JIT that doesn't make optimistic assumptions. By "bailing out to the interpreter" I mean "side exit" as

Hello developeRs, Apologies in advance for a rather long email, but to describe the problem, I need to step through many details. I have been working on a new dispatching system (futile.paradigm on CRAN) based on functional programming concepts that is an alternative to S3 and S4 dispatching. I use a declarative syntax using guard statements to control the dispatching between function variants. I

On 05/16/2018 04:49 PM, Philip Reames wrote: > All, > > TLDR: guards currently require reasoning about implicit control flow.  > LLVM struggles with implicit control flow within a basic block.  We > should redesign guards to admit this rather than trying to boil the > ocean. > > As you may be aware, LLVM currently has experimental support for a > construct called a

libswfdec/swfdec_as_frame.c | 17 ++++--------- libswfdec/swfdec_as_internal.h | 7 +++++ libswfdec/swfdec_as_interpret.c | 2 + libswfdec/swfdec_as_interpret.h | 2 + libswfdec/swfdec_as_object.c | 42 ++++++++++++++++++++++++---------- libswfdec/swfdec_as_script_function.c | 2 + libswfdec/swfdec_flash_security.c | 12 ++++-----

...winAsmParser.cpp:962:3: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation] if (Update > 255 || Update < 0) ^~ /home/dsl11/dev/llvm-upstream/src/lib/MC/MCParser/DarwinAsmParser.cpp:964:5: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘if’ Lex(); ^~~ ``` ``` /home/dsl11/dev/llvm-upstream/src/lib/Transforms/Scalar/LoopStrengthReduce.cpp: In member function ‘void {anonymous}::Cost::RateRegister(const llvm::SCEV*, llvm::SmallPtrSetImpl<const llvm::SCEV*>&, const llvm::Loop*, llvm::ScalarEvolution&,...

...execute at least once, if the preheader is reached.  How is what you need anything more than a loop header with a unique predecessor (preheader)? I'm not seeing the need for a guard block in what you said. Philip On 5/30/19 11:28 AM, Krzysztof Parzyszek via llvm-dev wrote: > On Hexagon, unguarded loops cannot be converted to hardware loops. > > If the loop's latch branch alone handles the iteration count, including the possibility of 0, then the loop cannot be converted to a hardware loop, because hardware loops must iterate at least once. If the entire loop is guarded against ze...

Sanjoy gave the long answer, let me give the short one. :) "deopt" argument bundles are used in the middle end, they are lowered into a statepoint, and generate the existing stackmap format. i.e. one builds on the other. On 02/18/2016 11:43 AM, Eric Christopher wrote: > Hi Sanjoy, > > A quick question here. With the bailing to the interpreter support > that you're

It was found that passing an invalid cpu number to pv_vcpu_is_preempted() might panic the kernel in a VM guest. For example, [ 2.531077] Oops: 0000 [#1] SMP PTI : [ 2.532545] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 2.533321] RIP: 0010:__raw_callee_save___kvm_vcpu_is_preempted+0x0/0x20 To guard against this kind of kernel panic, check is added to pv_vcpu_is_preempted() to

It was found that passing an invalid cpu number to pv_vcpu_is_preempted() might panic the kernel in a VM guest. For example, [ 2.531077] Oops: 0000 [#1] SMP PTI : [ 2.532545] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 2.533321] RIP: 0010:__raw_callee_save___kvm_vcpu_is_preempted+0x0/0x20 To guard against this kind of kernel panic, check is added to pv_vcpu_is_preempted() to

Given the following C++ code: ``` // test.cpp struct Foo { int public_foo(); int outside_foo(); [[gnu::always_inline]] int inline_foo() { int x = outside_foo(); if (x % 17) { x += 1; } return x; } [[gnu::noinline]] int inline_bar1() { int x = inline_foo(); if (x % 23) { x += 2; } return x; } [[gnu::noinline]] int inline_bar2() {

On 03/25/2019 12:40 PM, Juergen Gross wrote: > On 25/03/2019 16:57, Waiman Long wrote: >> It was found that passing an invalid cpu number to pv_vcpu_is_preempted() >> might panic the kernel in a VM guest. For example, >> >> [ 2.531077] Oops: 0000 [#1] SMP PTI >> : >> [ 2.532545] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 >> [ 2.533321]

On 03/25/2019 12:40 PM, Juergen Gross wrote: > On 25/03/2019 16:57, Waiman Long wrote: >> It was found that passing an invalid cpu number to pv_vcpu_is_preempted() >> might panic the kernel in a VM guest. For example, >> >> [ 2.531077] Oops: 0000 [#1] SMP PTI >> : >> [ 2.532545] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 >> [ 2.533321]