similar to: [LLVMdev] Loops Prevent Function Pointer Inlining?

But even for a very simple loop: int test1 (int *x, int *y, int *z, int k) { int sum = 0; for (int i = 10; i < k; i++) { z[i] = x[i] / y[i]; } return sum; } The initial value of induction variable is not zero after compiling with -O3 -mcpu=power8 x.cpp -S -c -emit-llvm -fno-unroll-loops (see bottom of the email for IR) Also I can write somewhat more complicated loop where step

I've CC'ed Chad Rosier as I think this behaviour is a side-effect of his revert of IndVarSimplify.cpp (git c6b1a7e577a0b9e9cff9f9b7ac35a2cde7c448d8, SVN 217962). The change basically makes the IndVar pass change: ; <label>:4 ; preds = %6, %0 %i.0 = phi i32 [ 0, %0 ], [ %11, %6 ] %5 = icmp eq i32 %i.0, 0 br i1 %5, label %6, label %17 To:

David/All, Just a quick question about NSW/NUW bits, if you've got a second. I noticed you've been doing a little work on this as of late. I have a bit of code that looks like the following: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1 %2 = add i64 %indvars.iv.next, -1 %tmp = trunc i64 %2 to i32 %cmp = icmp slt i32 %tmp, %0 br i1 %cmp, label %for.body, label

Hi, Mehdi, For example, I have this very simple source code: void foo( int n, int array_x[]) { for (int i=0; i < n; i++) array_x[i] = i; } After I use "clang -emit-llvm -o bc_from_clang.bc -c try.cc", I get bc_from_clang.bc. With my code (using LLVM IRbuilder API), I get bc_from_api.bc. Attachment please find thse two files. I also past the IR here.

Thanks for your point that out. I just add DataLayout in my code such as "mod->setDataLayout("e-m:e-i64:64-f80:128-n8:16:32:64-S128");", still no luck. I'm really confused about this. Do I need to add more passes before -loop-unroll? On Sat, Aug 22, 2015 at 11:36 AM, Mehdi Amini <mehdi.amini at apple.com> wrote: > > On Aug 22, 2015, at 7:27 AM, Xiangyang

Hi Gerolf, I think we have several (perhaps separable) issues here: 1. Do we have a canonical form for loops, preserved through the optimizer, that allows naturally-constructed loop nests to remain separable? 2. Do we forbid non-lowering transformations that turn vectorizable loops into non-vectorizable loops? 3. How do we detect cases where transformations cause a negative answer to either

I just subscribed this group. This is my first time to post a question (not sure if this is a right place for discussion) after I have a brief look at LLVM OPT (dev trunk). I would expect loop simplification and induction variable canonicalization pass (IndVarSimplify pass) should be able to convert the following loops into a simple canonical form, i.e., there is a canonical induction variable

Hi, InstCombine canonicalizes index operands (unless they are into struct types) to pointer size. The comment says: "If we are using a wider index than needed for this platform, shrink it to what we need. If narrower, sign-extend it to what we need. This explicit cast can make subsequent optimizations more obvious.". For our architecture, the canonicalization is a bit

On Wed, Jan 15, 2014 at 5:30 PM, Nadav Rotem <nrotem at apple.com> wrote: > Was the vectorizer successful in unrolling the loop in quantum_sigma_x? I > wonder if 'size’ is typically high or low. No. The vectorizer stated that it wasn't going to bother with the loop because it wasn't profitable. Specifically: LV: Checking a loop in "quantum_sigma_x" LV: Found a

Hi, Is the -indvars pass functional? I've done some small test to check it, but this fails to canonicalize: > int *x; > int *y; > int i; > ... > for (i = 1; i < 100; i+=2) { > x[i] = y[i] + 3; > } The IR produced after -indvars: > br label %for.cond > > for.cond: ; preds = %for.inc, %entry > %indvars.iv =

Hi All, I am trying to unroll the below loop, but couldn't as SCEV returns TripCount as 0. void foo(int x) { int p, i = 1; int mat[6][6][6]; for (p = x+3 ; p<= x+6 ;p++) mat[x][p][i] = mat[x][p][i] + 5; } For a quick reference I have added the generated IR compiled with clang using -O3. Please let me know if this is an known issue in SCEV or I am missing something here ? ;

----- Original Message ----- > From: "Hal Finkel" <hfinkel at anl.gov> > To: "Chandler Carruth" <chandlerc at google.com> > Cc: llvmdev at cs.uiuc.edu > Sent: Thursday, July 16, 2015 1:58:02 AM > Subject: Re: [LLVMdev] Improving loop vectorizer support for loops > with a volatile iteration variable > ----- Original Message ----- > >

Hello, I'm using LLVM to reason about memory safety of programs. One goal is to prove that certain array accesses are always safe. Currently, one of these proofs fails because of a missing no-signed-wrap (nsw) flag. I found that it has been "lost" during the SimplifyIndVar pass. Here's the example: int foo(int a[]) { int sum = 0; for (int i = 0; i < 1000; ++i)

Hi, I am new to MemorySSA and wanted to understand its capabilities. Hence I wrote the following program (test.c): int N; void test(int *restrict a, int *restrict b, int *restrict c, int *restrict d, int *restrict e) { int i; for (i = 0; i < N; i = i + 5) { a[i] = b[i] + c[i]; } for (i = 0; i < N - 5; i = i + 5) { e[i] = a[i] * d[i]; } } I compiled this program using

I have modified the example test case for UB error, still it didn’t unroll void foo(int x) { int p, i = 1; int mat[9][9][9]; for (p = (x+1) ; p < (x+3) ;p++) mat[x][p-1][i] = mat[x][p-1][i] + 5; } Regard, Deepali From: Kevin Choi [mailto:code.kchoi at gmail.com] Sent: Friday, September 16, 2016 1:20 PM To: Rai, Deepali Cc: llvm-dev at lists.llvm.org Subject: Re: [llvm-dev] SCEV

Andy, et al., If I start with C code like this: void foo(long k, int * restrict a, int * restrict b, int * restrict c) { if (k > 0) { for (int i = 0; i < 2047; i++) { a[i] = a[i + k] + b[i] * c[i]; } } } Clang -O3 will produce code like this: entry: %cmp = icmp sgt i64 %k, 0 br i1 %cmp, label %for.body.preheader, label %if.end for.body.preheader: br label

On Tue, Dec 19, 2017 at 9:10 AM, Siddharth Bhat via llvm-dev < llvm-dev at lists.llvm.org> wrote: > I could be entirely wrong, but from my understanding of memorySSA, each > def defines an "abstract heap state" which has the coarsest possible > definition - any write will be modelled as a "new heap state". > This is true for def-def relationships, but

On 21 October 2013 17:29, Arnold Schwaighofer <aschwaighofer at apple.com>wrote: > I don’t think that recognizing this as a reduction is going to get you > far. A reduction is beneficial if the value reduced is only truly needed > outside of a loop. > This is not the case here (we are storing/loading from the pointer). > Hi Arnold, Nadav, Let me resurrect this discussion a

Hi, I just tried llvm-3.8 (LLVM SVN Repository). With this version, -fno-rtti can help me to compile my code and -irce can help me to do a better job for loop unrolling. However, I still have one question. If I use Clang to compile a piece of c++ code to .bc and then use 'opt -loop-rotate -loop-unroll -irce', I can get what I want. I mean, there is no conditional branch at the end of each

On Oct 31, 2013, at 1:24 PM, Hal Finkel <hfinkel at anl.gov> wrote: > Andy, et al., > > If I start with C code like this: > > void foo(long k, int * restrict a, int * restrict b, int * restrict c) { > if (k > 0) { > for (int i = 0; i < 2047; i++) { > a[i] = a[i + k] + b[i] * c[i]; > } > } > } > > Clang -O3 will produce code like