[NFC][SCEV] Add tests related to bit masking (PR37793)
Summary:
Related to https://bugs.llvm.org/show_bug.cgi?id=37793, https://reviews.llvm.org/D46760#1127287
We'd like to do this canonicalization https://rise4fun.com/Alive/Gmc
But it is currently restricted by rL155136 / rL155362, which says:
```
// This is a constant shift of a constant shift. Be careful about hiding
// shl instructions behind bit masks. They are used to represent multiplies
// by a constant, and it is important that simple arithmetic expressions
// are still recognizable by scalar evolution.
//
// The transforms applied to shl are very similar to the transforms applied
// to mul by constant. We can be more aggressive about optimizing right
// shifts.
//
// Combinations of right and left shifts will still be optimized in
// DAGCombine where scalar evolution no longer applies.
```
I think these tests show that for *constants*, SCEV has no issues with that canonicalization.
Reviewers: mkazantsev, spatel, efriedma, sanjoy
Reviewed By: mkazantsev
Subscribers: sanjoy, javed.absar, llvm-commits, stoklund, bixia
Differential Revision: https://reviews.llvm.org/D48229
llvm-svn: 335101
2018-06-20 15:54:11 +08:00
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; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
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; RUN: opt -S -analyze -scalar-evolution < %s | FileCheck %s
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; The obvious case.
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define i32 @div(i32 %val) nounwind {
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; CHECK-LABEL: 'div'
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; CHECK-NEXT: Classifying expressions for: @div
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; CHECK-NEXT: %tmp1 = udiv i32 %val, 16
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; CHECK-NEXT: --> (%val /u 16) U: [0,268435456) S: [0,268435456)
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; CHECK-NEXT: %tmp2 = mul i32 %tmp1, 16
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2018-07-14 07:58:46 +08:00
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; CHECK-NEXT: --> (16 * (%val /u 16))<nuw> U: [0,-15) S: [0,-15)
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[NFC][SCEV] Add tests related to bit masking (PR37793)
Summary:
Related to https://bugs.llvm.org/show_bug.cgi?id=37793, https://reviews.llvm.org/D46760#1127287
We'd like to do this canonicalization https://rise4fun.com/Alive/Gmc
But it is currently restricted by rL155136 / rL155362, which says:
```
// This is a constant shift of a constant shift. Be careful about hiding
// shl instructions behind bit masks. They are used to represent multiplies
// by a constant, and it is important that simple arithmetic expressions
// are still recognizable by scalar evolution.
//
// The transforms applied to shl are very similar to the transforms applied
// to mul by constant. We can be more aggressive about optimizing right
// shifts.
//
// Combinations of right and left shifts will still be optimized in
// DAGCombine where scalar evolution no longer applies.
```
I think these tests show that for *constants*, SCEV has no issues with that canonicalization.
Reviewers: mkazantsev, spatel, efriedma, sanjoy
Reviewed By: mkazantsev
Subscribers: sanjoy, javed.absar, llvm-commits, stoklund, bixia
Differential Revision: https://reviews.llvm.org/D48229
llvm-svn: 335101
2018-06-20 15:54:11 +08:00
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; CHECK-NEXT: Determining loop execution counts for: @div
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;
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%tmp1 = udiv i32 %val, 16
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%tmp2 = mul i32 %tmp1, 16
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ret i32 %tmp2
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}
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define i32 @sdiv(i32 %val) nounwind {
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; CHECK-LABEL: 'sdiv'
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; CHECK-NEXT: Classifying expressions for: @sdiv
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; CHECK-NEXT: %tmp1 = sdiv i32 %val, 16
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; CHECK-NEXT: --> %tmp1 U: full-set S: [-134217728,134217728)
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; CHECK-NEXT: %tmp2 = mul i32 %tmp1, 16
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2018-07-14 07:58:46 +08:00
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; CHECK-NEXT: --> (16 * %tmp1)<nsw> U: [0,-15) S: [-2147483648,2147483633)
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[NFC][SCEV] Add tests related to bit masking (PR37793)
Summary:
Related to https://bugs.llvm.org/show_bug.cgi?id=37793, https://reviews.llvm.org/D46760#1127287
We'd like to do this canonicalization https://rise4fun.com/Alive/Gmc
But it is currently restricted by rL155136 / rL155362, which says:
```
// This is a constant shift of a constant shift. Be careful about hiding
// shl instructions behind bit masks. They are used to represent multiplies
// by a constant, and it is important that simple arithmetic expressions
// are still recognizable by scalar evolution.
//
// The transforms applied to shl are very similar to the transforms applied
// to mul by constant. We can be more aggressive about optimizing right
// shifts.
//
// Combinations of right and left shifts will still be optimized in
// DAGCombine where scalar evolution no longer applies.
```
I think these tests show that for *constants*, SCEV has no issues with that canonicalization.
Reviewers: mkazantsev, spatel, efriedma, sanjoy
Reviewed By: mkazantsev
Subscribers: sanjoy, javed.absar, llvm-commits, stoklund, bixia
Differential Revision: https://reviews.llvm.org/D48229
llvm-svn: 335101
2018-06-20 15:54:11 +08:00
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; CHECK-NEXT: Determining loop execution counts for: @sdiv
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;
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%tmp1 = sdiv i32 %val, 16
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%tmp2 = mul i32 %tmp1, 16
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ret i32 %tmp2
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}
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; Or, it could be a number of equivalent patterns with mask:
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; b) x & (-1 << nbits)
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; d) x >> nbits << nbits
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define i32 @mask_b(i32 %val) nounwind {
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; CHECK-LABEL: 'mask_b'
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; CHECK-NEXT: Classifying expressions for: @mask_b
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; CHECK-NEXT: %masked = and i32 %val, -16
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2018-07-14 07:58:46 +08:00
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; CHECK-NEXT: --> (16 * (%val /u 16))<nuw> U: [0,-15) S: [0,-15)
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[NFC][SCEV] Add tests related to bit masking (PR37793)
Summary:
Related to https://bugs.llvm.org/show_bug.cgi?id=37793, https://reviews.llvm.org/D46760#1127287
We'd like to do this canonicalization https://rise4fun.com/Alive/Gmc
But it is currently restricted by rL155136 / rL155362, which says:
```
// This is a constant shift of a constant shift. Be careful about hiding
// shl instructions behind bit masks. They are used to represent multiplies
// by a constant, and it is important that simple arithmetic expressions
// are still recognizable by scalar evolution.
//
// The transforms applied to shl are very similar to the transforms applied
// to mul by constant. We can be more aggressive about optimizing right
// shifts.
//
// Combinations of right and left shifts will still be optimized in
// DAGCombine where scalar evolution no longer applies.
```
I think these tests show that for *constants*, SCEV has no issues with that canonicalization.
Reviewers: mkazantsev, spatel, efriedma, sanjoy
Reviewed By: mkazantsev
Subscribers: sanjoy, javed.absar, llvm-commits, stoklund, bixia
Differential Revision: https://reviews.llvm.org/D48229
llvm-svn: 335101
2018-06-20 15:54:11 +08:00
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; CHECK-NEXT: Determining loop execution counts for: @mask_b
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;
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%masked = and i32 %val, -16
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ret i32 %masked
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}
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define i32 @mask_d(i32 %val) nounwind {
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; CHECK-LABEL: 'mask_d'
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; CHECK-NEXT: Classifying expressions for: @mask_d
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; CHECK-NEXT: %lowbitscleared = lshr i32 %val, 4
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; CHECK-NEXT: --> (%val /u 16) U: [0,268435456) S: [0,268435456)
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; CHECK-NEXT: %masked = shl i32 %lowbitscleared, 4
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2018-07-14 07:58:46 +08:00
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; CHECK-NEXT: --> (16 * (%val /u 16))<nuw> U: [0,-15) S: [0,-15)
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[NFC][SCEV] Add tests related to bit masking (PR37793)
Summary:
Related to https://bugs.llvm.org/show_bug.cgi?id=37793, https://reviews.llvm.org/D46760#1127287
We'd like to do this canonicalization https://rise4fun.com/Alive/Gmc
But it is currently restricted by rL155136 / rL155362, which says:
```
// This is a constant shift of a constant shift. Be careful about hiding
// shl instructions behind bit masks. They are used to represent multiplies
// by a constant, and it is important that simple arithmetic expressions
// are still recognizable by scalar evolution.
//
// The transforms applied to shl are very similar to the transforms applied
// to mul by constant. We can be more aggressive about optimizing right
// shifts.
//
// Combinations of right and left shifts will still be optimized in
// DAGCombine where scalar evolution no longer applies.
```
I think these tests show that for *constants*, SCEV has no issues with that canonicalization.
Reviewers: mkazantsev, spatel, efriedma, sanjoy
Reviewed By: mkazantsev
Subscribers: sanjoy, javed.absar, llvm-commits, stoklund, bixia
Differential Revision: https://reviews.llvm.org/D48229
llvm-svn: 335101
2018-06-20 15:54:11 +08:00
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; CHECK-NEXT: Determining loop execution counts for: @mask_d
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;
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%lowbitscleared = lshr i32 %val, 4
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%masked = shl i32 %lowbitscleared, 4
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ret i32 %masked
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}
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