similar to: [LLVMdev] Passing undef to functions

Hello, While investigating one of the existing tests (test/CodeGen/X86/tailcallpic2.ll), I ran into IR that produces some interesting code. The IR is very straightforward: define protected fastcc i32 @tailcallee(i32 %a1, i32 %a2, i32 %a3, i32 %a4) { entry: ret i32 %a3 } define fastcc i32 @tailcaller(i32 %in1, i32 %in2) { entry: %tmp11 = tail call fastcc i32 @tailcallee( i32 %in1, i32 %in2, i32

Hey Eli, On Thu, Feb 14, 2013 at 5:45 PM, Eli Bendersky <eliben at google.com> wrote: > Hello, > > While investigating one of the existing tests > (test/CodeGen/X86/tailcallpic2.ll), I ran into IR that produces some > interesting code. The IR is very straightforward: > > define protected fastcc i32 @tailcallee(i32 %a1, i32 %a2, i32 %a3, i32 > %a4) { > entry: >

>> While investigating one of the existing tests >> (test/CodeGen/X86/tailcallpic2.ll), I ran into IR that produces some >> interesting code. The IR is very straightforward: >> >> define protected fastcc i32 @tailcallee(i32 %a1, i32 %a2, i32 %a3, i32 >> %a4) { >> entry: >> ret i32 %a3 >> } >> >> define fastcc i32 @tailcaller(i32

Thanks Sean for the reference. I will go through it and see if i can implement it for generic boolean expression minimization. Regards, Suyog On Wed, Aug 13, 2014 at 2:30 AM, Sean Silva <chisophugis at gmail.com> wrote: > Re-adding the mailing list (remember to hit "reply all") > > > On Tue, Aug 12, 2014 at 9:36 AM, suyog sarda <sardask01 at gmail.com> wrote:

Sorry I missed that important detail. The relevant part of the command line is: -cc1 -S -triple i386-pc-win32 I don't expect it matters if it's for Windows or Linux in this case. On Fri, Sep 14, 2018 at 9:16 PM David Blaikie <dblaikie at gmail.com> wrote: > Can't say I've observed that behavior (though I'm just building from > top-of-tree rather than 6.0,

I've modified llvm to emit vc++ compatible SEH structures for my personality on x86/Windows and my handler works fine, but the only thing I can't figure out is how to call these funclets, they look like: Catch: "?catch$3@?0?m3 at 4HA": LBB4_3: # %BasicBlock26 pushl %ebp pushl %eax addl $12, %ebp movl %esp, -28(%ebp) movl $LBB4_5, %eax

Which performance guidelines are you referring to? I'm not that familiar with decade-old CPUs, but to the best of my knowledge, this is not true on current hardware. There is one specific circumstance where PUSHes should be avoided - for Atom/Silvermont processors, the memory form of PUSH is inefficient, so the register-freeing optimization below may not be profitable (see 14.3.3.6 and

When you enable -tailcallopt you get support for tail calls between functions with arbitrary stack space requirements. That means the calling convention has to change slightly. E.g the callee is responsible for removing it's arguments of the stack. The caller cannot transitively know the tail callee's tailcallee's requirement. Also care must be taken to make sure the stack stays

Hi everyone, I found that LLVM generates redundant code when calling functions with constant parameters, with optimizations disabled. Consider the following C code snippet: int foo(int x, int y); void bar() { foo(1, 2); foo(3, 4); } Clang/LLVM 6.0 generates the following assembly code: _bar: subl $32, %esp movl $1, %eax movl $2, %ecx movl $1, (%esp) movl $2, 4(%esp) movl %eax, 28(%esp) movl

Hello all, In r223757 I've committed a patch that performs, for the 32-bit x86 calling convention, the transformation of MOV instructions that push function arguments onto the stack into actual PUSH instructions. For example, it will transform this: subl $16, %esp movl $4, 12(%esp) movl $3, 8(%esp) movl $2, 4(%esp) movl $1, (%esp) calll _func addl $16, %esp

Hi Duncan, David, Sean. Thanks for your reply. > It'd be interesting if you could find a design that also treated these > the same: > > (B ^ A) | ((A ^ B) ^ C) -> (A ^ B) | C > (B ^ A) | ((B ^ C) ^ A) -> (A ^ B) | C > (B ^ A) | ((C ^ A) ^ B) -> (A ^ B) | C > > I.e., `^` is also associative. Agree with Duncan on including associative operation too.

Hi Arnold, Thanks for the insights. My comments below: On Thu, Feb 14, 2013 at 5:30 PM, Arnold Schwaighofer <aschwaighofer at apple.com> wrote: > When you enable -tailcallopt you get support for tail calls between functions with arbitrary stack space requirements. That means the calling convention has to change slightly. E.g the callee is responsible for removing it's arguments of

I was told that my writeup lacked an example and details so I reproduced the code that X uses and I was able to boil down the issue to a couple of lines of code. Sorry again for the length of this email. Code was compiled on OpenBSD with clang 3.0-release. ======================================================================== With -O0 which works as X expects:

Using LLVM 2.9, the following LLVM IR produces invalid x86 32 bit assembly (a misaligned SSE store). ; ModuleID = 'MisalignedStore' define void @MisalignedStore() nounwind readnone { entry: %v = alloca <4 x float>, align 16 store <4 x float> zeroinitializer, <4 x float>* %v, align 16 br label %post-block post-block: %f = alloca float ret void } If I feed

That's useful to know that the static compilation code path works. Furthermore, as expected from that: 52: c7 05 04 00 00 00 d5 00 00 00 movl $213, 4 00000054: IMAGE_REL_I386_DIR32 _foo It looks like the offset `4` of the second field of your struct is correct in the object file, so this does seem to be a problem in the JIT-specific linking/loading.

My code was hinky, but only in the sense that I was accidentally duplicating the definition variable in the module where the function was. With only the declaration in the second module loading the bitcode reproduces the issue. Managed an lli reproduction: $ cat jit-0.ll target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32" target triple =

Even if you can't implement such an algorithm sanely, ISTM that auto-generating this code from a table (or whatever), and choosing canonical results (to avoid a fixpoint issue), rather than what seems to be hand-additions of every possible set of minimizations on three variables, is still a better solution, no? At least then you wouldn't have human errors, and a growing file that makes

On Thu, Nov 10, 2011 at 6:13 PM, Aaron Dwyer <Aaron.Dwyer at imgtec.com> wrote: > Using LLVM 2.9, the following LLVM IR produces invalid x86 32 bit assembly > (a misaligned SSE store). > ; ModuleID = 'MisalignedStore' > define void @MisalignedStore() nounwind readnone { > entry: >   %v = alloca <4 x float>, align 16 >   store <4 x float>

Hi, I have run into the following strange behavior and wanted to ask for some advice. For the C program below, function sum() gets inlined in foo() but the code generated looks very suboptimal (the code is an extract from a larger program). Below I show the 32-bit x86 assembly as produced by the demo page on the llvm home page ("Output A"). As you can see from the assembly, after

Hi, I tried that before, it produces .text ALIGN 16 .globl _main _main: ; @main ; BB#0: ; %entry subl $20, %esp movl $0, 16(%esp) movl 24(%esp), %eax movl %eax, 12(%esp) movl 28(%esp), %eax movl %eax, 8(%esp) movl $($_.str),