similar to: [LLVMdev] [LLVMDev] Register Allocation

On Oct 28, 2010, at 9:40 AM, Jeff Kunkel wrote: > I have noticed quite a few changes regarding register allocation. I am > wondering will there be support for radically different data > structures other than the LiveIntervals, Virtual Register Map, etc? Not any more than we already have. If anything, these data structures are going to be simplified. For instance, VirtRegMap's

On Aug 15, 2010, at 5:12 PM, Silvio Ricardo Cordeiro wrote: > Is there a way for me to collect statistics about the number of loads/stores added by the "linearscan" register allocator (just like can be done with the "local" allocator)? I still haven't grokked very well the interaction between RALinScan and Spiller... Should I add those two statistics to the

Hi, Is there a way for me to collect statistics about the number of loads/stores added by the "linearscan" register allocator (just like can be done with the "local" allocator)? I still haven't grokked very well the interaction between RALinScan and Spiller... Should I add those two statistics to the spiller's class? Thanks, -- Silvio Ricardo Cordeiro --------------

Hi Quentin and llvm-dev, I've got a regalloc-related question that you might have an opinion or answer about. In our out-of-tree target we've been doing some bundling before register allocation for quite some time now, and last night a new problem popped up. What the fix should be depends on if this bundle is legal or not: BUNDLE %vreg39<imp-def,dead> *

I'm trying to compute and print a weighted spill cost based upon the execution frequency of the basic block where the spill is inserted. My goal is to analyse what effect scheduling changes have on the sum of this weighted spill cost in some benchmarks. I've experimented doing this directly before a spill is inserted in InlineSpiller.cpp using MBFI.getBlockFreq()

Hello, I've been trying to figure out how to reproduce the results of a single clang -O3 compilation to a binary with a multi-step process using opt. Specifically I have: clang -O3 foo.c -o foo.exe which I want to replicate with: clang -O0 -c -emit-llvm foo.c opt -O3 foo.bc -o foo_o.bc clang foo_o.bc -o foo.exe Any hints / suggestions on what additional flags I need to produce the same

Hi, Can anyone help me with the stack slot coloring optimization? This corresponding file is /lib/codegen/stackslotcoloring.cpp. It is said this optimization was for stack slot overlay for frame size reduction, after register allocation phase. And this transformation pass relies on the LiveStack analysis pass. How, when checking the source code, it seems the LiveStack analysis has not been

Hal's advice helps me a lot to understand the implementation much better. Thanks so much! So, now I am able to state my problem more clearly: 1) There are two kinds of locals, i.e., the local variables originated from the source code (like C/C++), and the compilation generated temporaries. After instruction selection phase, the former is seen as frame indexes, while the latter is seen as

Awesome, thanks! I'd like to have the last step (llc in your example) not perform additional optimization passes, such as O3, and simply use the O3 pass from opt in the previous line. Do you happen to know if I should use 'llc -O0 foo_o.bc -o foo.exe' instead to achieve this? On Thu, Jul 2, 2020 at 6:35 PM Mehdi AMINI <joker.eph at gmail.com> wrote: > > > On Thu,

Hi Quentin, Thanks for the reply! However, we are not using any profiling-based compilation in our current work. We are assuming that, if PGO is disabled, the register allocator (and any other pass that needs basic block frequency info) will be basing its decisions on some kind of *static" basic block frequency info that are based on some compile-time heuristics and at least capture loop

Hello to all LLVM developers. I'm developing a register allocator using LLVM, my allocator has a local search phase: given a solution (assignment of virtual registers to physical registers or memory) generated in the first phase of the algorithm, some movements are applied to this solution in order to find a better solution. To apply such movements, I need to unassign a virtual register from

Hi, I'm working on the implementation of Extended Linear Scan register allocator as described by Sarkar & Bodik. One of the interesting features of their algorithm is the possibility to allocate different physical registers to different live-ranges of the same LiveInterval. Of course, it may require some glue code to be inserted in cases, where different physical regs were assigned to

On Feb 27, 2009, at 7:20 AM, Roman Levenstein wrote: > Hi, > > I'm working on the implementation of Extended Linear Scan register > allocator as described by Sarkar & Bodik. > One of the interesting features of their algorithm is the possibility > to allocate different physical registers to different live-ranges of > the same LiveInterval. Of course, it may require

Hi Evan, Thanks a lot for your reply! 2009/2/27 Evan Cheng <evan.cheng at apple.com>: > > On Feb 27, 2009, at 7:20 AM, Roman Levenstein wrote: > >> Hi, >> >> I'm working on the implementation of Extended Linear Scan register >> allocator as described by Sarkar & Bodik. >> One of the interesting features of their algorithm is the possibility

Hi Jonas, Thanks for your patience. After spending some time looking at the additional output you gave me, I agree that your fix is the right one. I was worried that this problem may arise because we were spilling not real user, but in fact what I thought was the problem is an optimization we could do :). See my comments inlined for a few nitpicks before you commit. Thanks again, -Quentin On

Hi, I have run into a test case on an out-of-tree target where PBQP fails to complete register allocation after "Attempting to spill already spilled value" (the triggered assert in InlineSpiller::spill(). First, the original LiveInterval is spilled. It is a load of a symbol into a narrow register class, i.e. a subset of the class of address registers. InlineSpiller decides to

Hi Quentin, I have tried to find a test case for an official target, but failed. It seems to be a rare case. To do it, I added the 'else' clause in the following: ... if (VNI->def == OrigVNI->def) { DEBUG(dbgs() << "orig phi value\n"); SVI->second.DefByOrigPHI = true; SVI->second.AllDefsAreReloads = false; propagateSiblingValue(SVI); continue;

Hello Mentors, I am currently finding bug in Local Function related optimization due to which runtime failures are observed in some test cases, as those test cases are containing very large function with recursion and object oriented code so I am not able to find a pattern which is causing failure. So I tried following simple case to understand expected behavior from this optimization. Consider

Hi, I have encountered a test case where InlineSpiller generates bad code. A register is reloaded but never spilled, and I suspect a bug in InlineSpiller. A register is live over a loop that also have two inner loops. It is not used or defined over the inner loops. It is split into two sibling registers, where one covers just the inner loops interval, which is then spilled. In spill(),

Spiller::Spill( LiveInterval *li, SmallVectorImpl<LiveInterval*> &newIntervals, const SmallVectorImpl<LiveInterval*> &spillIs ); has two reference vectors which contain a small list of Live Intervals. What is the register allocator's job to do with these intervals other than analysis. What more needed other than to know