similar to: [LLVMdev] Stack layout in the x86 back-end

On Tue, 9 Oct 2007, Sarah Thompson wrote: > ideally, I'd like a block that encompasses everything from the function > parameters up to the current top-of-stack including spilled registers. > Is this feasible? Hi Sarah, I'm not sure how much of this is possible. You're guaranteed that each function stack frame is itself contiguous (including spilled regs), but there

Hi everyone, I'm curious about the constraints that come with the usage of llvm.stacksave/llvm.stackrestore. Specifically I was wondering what the contract of their usage was with respect to SSA variables defined after llvm.stacksave. It seems to me that they could get spilled to a stack slot, which I'm concerned stackrestore might mess up. Is this a valid concern? Thanks, Keno

On 2018-05-11 02:28, Andrew Kelley via llvm-dev wrote: > In the Zig frontend, we know at compile-time the entire call graph. > This means we know stack size for all functions and therefore the > upper bound stack usage. > > [snip] > 1. Is there a way to accomplish this with existing LLVM API? You should use the @llvm.stacksave and @llvm.stackrestore intrinsic. It is only legal

In the Zig frontend, we know at compile-time the entire call graph. This means we know stack size for all functions and therefore the upper bound stack usage. Recursive calls can have a runtime-decided stack usage, and therefore I am adding a frontend feature that will heap-allocate memory to use for some function calls. The idea is that recursion adds cycles to the call graph, and we know at

Hi everyone, We seem to have allowed our documented target-independent intrinsics to acquire a somewhat-haphazard naming system, and I think we should standardize on one convention. All of the intrinsics have 'llvm.' as a prefix, and some also have some additional prefix 'llvm.dbg.', 'llvm.eh.', 'llvm.experimental.', etc., but after that we lose consistency. When

Hi, I have two problems regarding the llvm.stackrestore intrinsic. I'm running on 3.0, but a quick test on trunk also showed the same behavior. First problem: --------------- I have code like: tmp1 = call llvm.stacksave() tmp2 = alloca [do some stuff with tmp2] call llvm.stackrestore(tmp1) [some other stuff] tmp3 = call llvm.stacksave() tmp4 = alloca [do some stuff

Hi LLVM folks, To properly implement pass-by-value in the Microsoft C++ ABI, we need to be able to take the address of an outgoing call argument slot. This is http://llvm.org/PR5064 . Problem ------- On Windows, C structs are pushed right onto the stack in line with the other arguments. In LLVM, we use byval to model this, and it works for C structs. However, C++ records are also passed this

I find this pattern as below from <llvm-source-tree>/test/CodeGen/Mips/alloca.ll. Do you know what front end pattern can be translated into this pattern alloca with variable argument %size as below? Can some one help me? I am writing the llvm backend document --http://jonathan2251.github.com/lbd/index.html now. %tmp1 = alloca i8, i32 %size, align 4 // has %size variable, not pattern,

On Thu, May 10, 2018 at 10:35 PM, whitequark <whitequark at whitequark.org> wrote: > On 2018-05-11 02:28, Andrew Kelley via llvm-dev wrote: > >> In the Zig frontend, we know at compile-time the entire call graph. >> This means we know stack size for all functions and therefore the >> upper bound stack usage. >> >> [snip] >> 1. Is there a way to

Hi, I've tracked the first problem (mentioned in my previous email, quoted below) down further, ending up in the handling of alloca in LoopRotation.cpp (from trunk): // If the instruction's operands are invariant and it doesn't read or write // memory, then it is safe to hoist. Doing this doesn't change the order of // execution in the preheader, but does

2012/2/3 Patrik Hägglund <patrik.h.hagglund at ericsson.com>: > Hi, > > I've tracked the first problem (mentioned in my previous email, quoted > below) down further, ending up in the handling of alloca in > LoopRotation.cpp (from trunk): > >      // If the instruction's operands are invariant and it doesn't read > or write >      // memory, then it is

Bringing this back up for discussion on handling exceptions. According to the inalloca design <https://llvm.org/docs/InAlloca.html>, there should be a stackrestore after an invoke in both the non-exceptional and exceptional case (that doesn't seem to be happening in some cases as we've seen, but that's beside the point). Does it make sense to model a preallocated call as

Hi! Sorry for delay, just returned from vacation. On 12/11/15 23:44, Kostya Serebryany via llvm-dev wrote: > +Maxim and Yuri, as I think this is their code. > > On Thu, Nov 12, 2015 at 3:02 AM, Jay Foad <jay.foad at gmail.com > <mailto:jay.foad at gmail.com>> wrote: > > (Resending with the correct mailing list address.) > > Hi, > > Currently

On Sat, Mar 28, 2020 at 2:20 PM Eli Friedman <efriedma at quicinc.com> wrote: > This would specifically be for cases where we try to rewrite the > signature? I would assume we should forbid rewriting the signature of a > call with an operand bundle. And once some optimization drops the bundle > and preallocated marking, to allow such rewriting, the signature doesn’t > need

Hello, So, I have this testcase: void f(int n, int x[]) { if (n < 0) return; int a[n]; for (int i = 0; i < n; i++) a[i] = x[n - i - 1]; for (int i = 0; i < n; i++) x[i] = a[i] + 1; } that, compiled with -O1/-Os for AArch64 and X86, generates machine code, which fails to properly restore the stack pointer upon function return.

Jay, do you have a PowerPC64 target? If so, could you please check attached patch on PPC box? This is a draft patch, but it would be nice to make sure that we are moving to right direction here. Thanks, -Maxim On 18/11/15 00:12, Jay Foad wrote: >>> Currently test/asan/TestCases/alloca_vla_interact.cc is XFAILed for >>> powerpc64. I've had a look at why it

Hi, guys! I write a virtual machine which uses LLVM as back-end code generator. The following function code causes strange "UNREACHABLE executed!" error: define void @p1(%1*) { %2 = call i8* @llvm.stacksave() %3 = alloca %0 %4 = getelementptr %0* %3, i64 1 %5 = ptrtoint %0* %3 to i64 %6 = ptrtoint %0* %4 to i64 %7 = sub i64 %6, %5 %8 = bitcast %0* %3 to i8* call void

How do you handle this during codegen? One problem is avoid stack changes (like spills). Another is coordinating things that are using allocas and those that are not but end up in the stack. Consider void foo(int arg1, int arg2, int arg3, ....CXXTypeWithCopyConstructor argn, int argp1...) You will need an alloca for argn, but the ABI also requires it to be next to the plain integers that

Nyx wrote: > Hello, > > I would just like to ask if it's possible to explicitly free allocas. This > is because I need to call functions that take structs of different sizes as > input, (possibly inside of loops) and I would rather avoid a stack overflow. You can't explicitly free a specific alloca, but you can use the llvm.stacksave and llvm.stackrestore intrinsics to

Hi, guys. I have a beginner's question. The virtual machine I develop have instructions to dynamically allocate variable in stack and to free it (consistency of such instructions is checked before the actual jitting). To allocate memory in stack we have alloca IR instruction, but I didn't find any instruction to free it (such variables will be freed only when an enclosing function will