similar to: [LLVMdev] "Machine LICM" for Constants?

Yes machine-licm can and should hoist constant materialization instructions out of the loop. If it's not doing that, it's probably because the target is not modeling the instruction correctly. I would walk through MachineLICM::IsLoopInvariantInst() in the debugger to figure it out. You can also try compiling the same bitcode for a target like ARM or X86 as a comparison. Evan On Mar 7,

Thanks for the tip! I looked into it and it looks like the problem as of SVN HEAD is that the lui and ori instructions in Mips are considered cheap (1-cycle def-use latency) by MachineLICM::IsCheapInstruction(), but are not trivially materializable because their register operands are not always available. This makes MachineLICM::IsProfitableToHoist() return false, preventing the hoist even

On 04/29/2012 01:19 PM, Evan Cheng wrote: > On Apr 24, 2012, at 11:48 PM, Fan Dawei wrote: > >> For the following code fragment, >> >> ;<label>:27 ; preds = %27, %entry >> %28 = load volatile i32* inttoptr (i64 2149581832 to i32*), align 8 >> %29 = icmp slt i32 %28, 0 >> br i1 %29, label %27, label

On Apr 24, 2012, at 11:48 PM, Fan Dawei wrote: > For the following code fragment, > > ; <label>:27 ; preds = %27, %entry > %28 = load volatile i32* inttoptr (i64 2149581832 to i32*), align 8 > %29 = icmp slt i32 %28, 0 > br i1 %29, label %27, label %loop.exit > > loop.exit: ; preds = %27

For the following code fragment, ; <label>:27 ; preds = %27, %entry %28 = load volatile i32* inttoptr (i64 2149581832 to i32*), align 8 %29 = icmp slt i32 %28, 0 br i1 %29, label %27, label %loop.exit loop.exit: ; preds = %27 llc will generate following MIPS code, $BB0_1: lui $3, 32800 ori $3, $3, 1032 lw

--- src/libFLAC/bitwriter.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/src/libFLAC/bitwriter.c b/src/libFLAC/bitwriter.c index 651440d..7da4b15 100644 --- a/src/libFLAC/bitwriter.c +++ b/src/libFLAC/bitwriter.c @@ -43,12 +43,11 @@ /* Things should be fastest when this matches the machine word size */ /* WATCHOUT: if you change this

I didn't have Mips board. I compile as the commands and check the asm output as below. 1. Question: The distance of caller arg[4] and arg[5] is 4 bytes. But the the callee get every arg[] by 8 bytes offset (arg_ptr1+8 or arg_ptr2+8). I assume the #BB#4 and #BB#5 are the arg_ptr which is the pointer to access the stack arguments. 2. Question: Stack memory 28($sp) has no initial value. If

Does it make a difference if you give the "-target" option to clang? $ clang -target mips-linux-gnu ch8_3.cpp -o ch8_3.bc -emit-llvm -c The .s file generated this way looks quite different from the one in your email. On Tue, Feb 19, 2013 at 5:06 PM, Jonathan <gamma_chen at yahoo.com.tw> wrote: > I didn't have Mips board. I compile as the commands and check the asm >

i am getting seg fault on functions like I->eraseFromParent also. I'm assuming that the problem comes when i change the loop structure. On Thu, Nov 18, 2010 at 4:05 AM, Sreeraj a <writetosrj at gmail.com> wrote: > The funny thing is that i am manually able to hoist the Loop invariant > instruction to the basicBlock terminator, by editing the human readable form > and then

The funny thing is that i am manually able to hoist the Loop invariant instruction to the basicBlock terminator, by editing the human readable form and then using llvm-as to convert it into bytecode. On Thu, Nov 18, 2010 at 4:01 AM, Chris Lattner <clattner at apple.com> wrote: > > On Nov 17, 2010, at 1:38 PM, Sreeraj a wrote: > > > Thanks Chris, > > > > I was

Which part of the generated code do you think is not correct? Could you be more specific? I compiled this program with clang and ran it on a mips board. It returns the expected result (21). On Tue, Feb 19, 2013 at 4:15 AM, Jonathan <gamma_chen at yahoo.com.tw> wrote: > I check the Mips backend for the following C code fragment compile result. > It seems not correct. Is it my

I check the Mips backend for the following C code fragment compile result. It seems not correct. Is it my misunderstand or it's a bug. //ch8_3.cpp #include <stdarg.h> int sum_i(int amount, ...) { int i = 0; int val = 0; int sum = 0; va_list vl; va_start(vl, amount); for (i = 0; i < amount; i++) { val = va_arg(vl, int); sum += val; } va_end(vl);

What are the correct target description side effect flags for instructions which may trap (e.g. divide / remainder)? The divide instruction in my backend currently has no flags set. I've enabled the MachineLICM pass and it's causing a miscompilation by hoisting a divide by zero instruction out of the loop. Clearly this pass needs to be made aware that this is not safe. The current

On 10 May 2014, at 13:53, Tim Northover <t.p.northover at gmail.com> wrote: > It doesn't make sense for everything though, particularly if you want > target-specific IR to simply not exist. What would you map ARM's > "ldrex" to on x86? This isn't a great example. Having load-linked / store-conditional in the IR would make a number of transforms related to

Jay Foad wrote: >> I'm linking a program (my ellsif driver) that basically brings in most >> of the LLVM stuff: bitcode reading, optimizations, linking, and target >> code generation. >> >> All of a sudden, I'm getting the following when I run: >> [~/elsa/ellsif] dev% ./ellsif -v test/ofmt.i test/sieve.i -time-actions >> -O5 >>

my changed code. namespace { class MyLoopPass:public LoopPass { bool changed; public: static char ID; Loop* curLoop; // AnalysisType* AA; DominatorTree* DT; LoopInfo* LI; MyLoopPass() : LoopPass(ID){} bool isLoopInvariantInst(Instruction &I) ; bool runOnLoop(Loop * L, LPPassManager &lpm); virtual void getAnalysisUsage(AnalysisUsage &AU) const {

On 6 July 2011 02:31, D S Khudia <daya.khudia at gmail.com> wrote: >   %0 = load i32* %i, align 4 >   %HV14_ = getelementptr inbounds [100 x i32]* %a, i32 0, i32 %0 >   %1 = getelementptr inbounds [100 x i32]* %a, i32 0, i32 %0 >   %HVCmp7 = icmp ne i32* %1, %HV14_ >   br i1 %HVCmp7, label %relExit, label %bb.split > > So that HV14_ is a new instruction and I am

Thanks again. I executed the following command line llc -O3 comb.ll.bc -debug-pass=Arguments and got Pass Arguments: -targetdata -targetpassconfig -no-aa -tbaa -targetlibinfo -basicaa -collector-metadata -machinemoduleinfo -machine-branch-prob -preverify -domtree -verify -loops -loop-simplify -scalar-evolution -loop-simplify -iv-users -loop-reduce -gc-lowering -unreachableblockelim

Hello, I am duplicating few instructions in a basic block and splitting it. The following is an example. bb: ; preds = %bb1 %0 = load i32* %i, align 4 %1 = getelementptr inbounds [100 x i32]* %a, i32 0, i32 %0 store i32 0, i32* %1, align 4 %2 = load i32* %i, align 4 %3 = getelementptr inbounds [100 x i32]* %last_added, i32 0, i32 %2 store

Does LLVM have loop multiversioning ? it seems it does not with clang++ -O3 -mllvm -debug-pass=Arguments program.c -c bash-4.1$ clang++ -O3 -mllvm -debug-pass=Arguments fast_algorithms.c -c clang-3.6: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated Pass Arguments: -datalayout -notti -basictti -x86tti -targetlibinfo -no-aa -tbaa -scoped-noalias