similar to: [LLVMdev] Value of structure passed byval to a recurse function not initialized when accessed through GDB

Hi David, I think it might not be exactly PR13303 which might be causing the corruption of struct when accessed through GDB. This seems to be an ABI problem in clang. The problem seems to be that when we have pass by value of struct (having indirect arguments) stack is not aligned properly. I tried realigning the stack for indirect arguments in(TargetInfo.cpp) - ABIArgInfo

Hi Relph, I'm trying to print the value of 'a' while executing a.s = --depth; I have used break line number instead of break function so that the initial prologue part gets executed. The problem seems to be happening when parameters are pushed into stack and we call a function recursively. For example in the code when we have a int s; inside the struct instead of short s; gdb is able

This seems to be another case of PR13303 - since GDB can't figure out where to break for this function based on the debug info (you'll notice when you "break recurse" that it's not breaking on a line or source file, just an address) it's breaking at the very start, before the prologue I'm about to commit a fix to this. On Tue, Dec 4, 2012 at 5:34 AM, Karthik Bhat

On Thu, Dec 6, 2012 at 12:33 AM, Karthik Bhat <karthikthecool at gmail.com> wrote: > Hi David, > > I think it might not be exactly PR13303 which might be causing the > corruption of struct when accessed through GDB. > This seems to be an ABI problem in clang. > The problem seems to be that when we have pass by value of struct > (having indirect arguments) stack is not

Karthik, At what point within recurse() are you asking gdb to display the value of argument a? What I'm wondering about is if the debug information gdb is using to get at a might not be correct at the particular point you are checking a, particularly if that is before the prolog has completed execution. The way debug information for arguments pushed on the stack is represented in

Hi - help! I have read through previous threads on the subject of 'byval' e.g. https://groups.google.com/forum/#!topicsearchin/llvm-dev/Exact$20meaning$20of$20byval/llvm-dev/cyRZyXcMCNI https://groups.google.com/forum/#!topicsearchin/llvm-dev/$20byval/llvm-dev/uk4uiK93jeM https://groups.google.com/forum/#!topicsearchin/llvm-dev/byval/llvm-dev/46Tv0lSRwBg and read through code

Hi Robert, > I tried adding to the XCoreCallingConv.td: > CCIfByVal<CCPassByVal<0,4>> // pushes pointer to the stack This looks sensible to me. After that it comes down to cooperation between XCoreISelLowering's LowerFormalArguments and LowerCall functions. LowerFormalArguments is at the beginning of a function and is responsible for taking arguments out of

Hi Tim, Thank you for the input. I think I follow you. I believe the LowerCall is doing what it needs to do - passing pointer either on the stack or in register as per ABI. The LowerFormalArguments() is where I am stuck. LowerFormalArguments () calls CCInfo.AnalyzeFormalArguments(Ins, CC_XCore), which calls the CC_XCore(). This is where I placed the CCIfByVal<CCPassByVal<0,4>> which

Hi All, I'm looking into this simple inline assembly code. Were we copy contents on data to eax,ebx,ecx and edx and later copy them back from the registers to data. Test Case - #include <stdio.h> int data[] = { 0x14131211, 0x24232221, 0x34333231, 0x44434241, }; int main (int argc, char **argv) { asm ("mov 0(%0), %%eax\n\t" "mov 4(%0), %%ebx\n\t"

Hi, > I believe the LowerCall is doing what it needs to do - passing pointer either on the stack or in register as per ABI. >From very quick test-cases with no understanding of XCore, that looks plausible. > LowerFormalArguments () calls CCInfo.AnalyzeFormalArguments(Ins, CC_XCore), which calls the CC_XCore(). > This is where I placed the CCIfByVal<CCPassByVal<0,4>>

Hi Tim, Correction to my last email. What I should have said is that the new pointer is used by the callee rather than the original byVal pointer arg. (the byVal pointer arg remains but is not used by the callee). viz: define void @f1(%struct.tag* byval) { entry: %st = alloca %struct.tag, align 4 %1 = bitcast %struct.tag* %st to i8* %2 = bitcast %struct.tag* %0 to i8* call void

Hi Tim, Thought about it last night and was coming to the same conclusion. 1. it cant be done at the end during lowering (target backend). 2. it should be part of llvm as the byVal needs to be handled. As a twist, I have been told that llvm-gcc can lower byVal into memcpy in the callee. I may take a look at this. I wonder if it ever emits 'byVal'... I still feel I don't understand

On Feb 11, 2013, at 12:02 PM, David Blaikie <dblaikie at gmail.com> wrote: > Beyond that, though, I've hit one hierarchy in the Static Analyzer > that does this as well: ProgramPoint. On IRC Jordan Rose mentioned > that there's another more pervasive use of this pattern in the Static > Analyzer, the SVal hierarchy. > > So, Ted, how objectionable would it be for me

On Wed, Dec 5, 2012 at 1:06 PM, David Blaikie <dblaikie at gmail.com> wrote: > On Thu, Nov 29, 2012 at 8:16 PM, Richard Smith <richard at metafoo.co.uk> wrote: >> On Thu, Nov 29, 2012 at 7:43 PM, Eli Friedman <eli.friedman at gmail.com> >> wrote: >>> >>> On Thu, Nov 29, 2012 at 3:49 PM, David Blaikie <dblaikie at gmail.com> wrote:

On 10/03/2011 09:36 PM, Villmow, Micah wrote: > One of the projects I am working on with others is to make LLVM-IR endian agnostic. > > > > So, I am sending out this proposal for feedback to the LLVM community. I’ve attached > > pretty version of the proposal in PDF format and pasted a 80-column safe text version > > below. > > > > A second smaller

I was thinking of something along the lines of: // SCRIPT-POSIX: posix/aggregate-indirect-arg.s // SCRIPT-WIN: win/aggregate-indirect-arg.s class SVal { public: ~SVal() {} const void* Data; unsigned Kind; }; void bar(SVal &v) {} class A { public: void foo(SVal v) { bar(v); } }; int main() { SVal v; v.Data = 0; v.Kind = 2142; A a; a.foo(v); return 0; } Then, you could

Hi Robert, suppose you have a "byval" argument with type T*, and the caller passes a T* called %X for it, while in the callee the argument is called %Y. The IR level semantics are: (1) a copy should be made of *%X. Whether the callee or the caller makes the copy depends on the platform ABI. (2) in the callee, %Y refers to the address of this copy. There are many ways (1) can be

Hi Kevin, To get some portion of a constant immediate you can use SDNodeXForms to transform constant SDNodes into other values. For a worked example, in the MIPS backend we use this for constant synthesis by materializing the value into a register: (From lib/Target/MipsInstrInfo.td): // Transformation Function - get the lower 16 bits. def LO16 : SDNodeXForm<imm, [{ return getImm(N,

Hi all, I apply "optim" to the function "obj", which minimizes the goodness of fit statistic and obtains Pearson minimum chi-squared estimate for x[1], x[2] and x[3]. The vector "fr" contains the four observed frequencies. Since "fr[i]" appears in the denominator, I would like to substitute "0" in the sum if fr[i]=0. I tried an

Hi Tim, I may be missing something but using CCPassByVal is moving the pointer onto the stack - not what I'm after. I need to add an operation to the function prolog that actually makes a copy of the pointed to data. It is the responsibility of the callee to make the copy, not the caller - hence my trouble. (currently the callee can corrupt the original data viz pass-by-reference!) This