Hello,
I have this piece of code:
int main() {
int m = 0;
// int i, j, k;
// int N = f()%10;
for (int l = 0; l < 1000; l+=4)
printf("%d", l);
I am sure, that llvm is capable to convert this into canonical induction
variable, but even with O3
define i32 @main() #0 {
br label %2
; <label>:1 ; preds = %2
ret i32 0
; <label>:2 ; preds = %0, %2
%l.01 = phi i32 [ 0, %0 ], [ %4, %2 ]
%3 = tail call i32 (i8*, ...) @printf(i8* nonnull getelementptr inbounds
([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32 %l.01)
%4 = add nuw nsw i32 %l.01, 4
%5 = icmp slt i32 %4, 1000
br i1 %5, label %2, label %1
}
I have this assembler.
I know there is indvars2 pass ( it is under llvm license but used only in
LegUp project - as I understood, surfing the Internet), which is good in
changing induction variables.
How can I achieve that this cycle will have a canonical indvar?
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The files of this strange pass are described here http://reviews.legup.org/rLEGUP54ca7c2bb15d84116baf47bce67256d3803720d9 . I wonderwhy the most uptodate -indvars pass can't do the same. 2017-08-09 14:18 GMT+02:00 Anastasiya Ruzhanskaya < anastasiya.ruzhanskaya at frtk.ru>:> Hello, > I have this piece of code: > int main() { > int m = 0; > // int i, j, k; > // int N = f()%10; > for (int l = 0; l < 1000; l+=4) > printf("%d", l); > > I am sure, that llvm is capable to convert this into canonical induction > variable, but even with O3 > define i32 @main() #0 { > br label %2 > > ; <label>:1 ; preds = %2 > ret i32 0 > > ; <label>:2 ; preds = %0, %2 > %l.01 = phi i32 [ 0, %0 ], [ %4, %2 ] > %3 = tail call i32 (i8*, ...) @printf(i8* nonnull getelementptr inbounds > ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32 %l.01) > %4 = add nuw nsw i32 %l.01, 4 > %5 = icmp slt i32 %4, 1000 > br i1 %5, label %2, label %1 > } > > I have this assembler. > I know there is indvars2 pass ( it is under llvm license but used only in > LegUp project - as I understood, surfing the Internet), which is good in > changing induction variables. > > How can I achieve that this cycle will have a canonical indvar? >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170809/a1db4c87/attachment.html>
This support was removed years ago from indvars. We don't need canonical induction variables any more as all analysis are done on SCEVs. The SCEV generator can transform them even without the need for explicit canonical induction variables. Best, Tobias On Wed, Aug 9, 2017, at 14:23, Anastasiya Ruzhanskaya via llvm-dev wrote:> The files of this strange pass are described here > http://reviews.legup.org/rLEGUP54ca7c2bb15d84116baf47bce67256d3803720d9 > . > I wonderwhy the most uptodate -indvars pass can't do the same. > > 2017-08-09 14:18 GMT+02:00 Anastasiya Ruzhanskaya < > anastasiya.ruzhanskaya at frtk.ru>: > > > Hello, > > I have this piece of code: > > int main() { > > int m = 0; > > // int i, j, k; > > // int N = f()%10; > > for (int l = 0; l < 1000; l+=4) > > printf("%d", l); > > > > I am sure, that llvm is capable to convert this into canonical induction > > variable, but even with O3 > > define i32 @main() #0 { > > br label %2 > > > > ; <label>:1 ; preds = %2 > > ret i32 0 > > > > ; <label>:2 ; preds = %0, %2 > > %l.01 = phi i32 [ 0, %0 ], [ %4, %2 ] > > %3 = tail call i32 (i8*, ...) @printf(i8* nonnull getelementptr inbounds > > ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32 %l.01) > > %4 = add nuw nsw i32 %l.01, 4 > > %5 = icmp slt i32 %4, 1000 > > br i1 %5, label %2, label %1 > > } > > > > I have this assembler. > > I know there is indvars2 pass ( it is under llvm license but used only in > > LegUp project - as I understood, surfing the Internet), which is good in > > changing induction variables. > > > > How can I achieve that this cycle will have a canonical indvar? > > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev