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llvm-mirror/test/Transforms/InstSimplify
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Roman Lebedev ca7b7a7578 [InstSimplify] simplifyUnsignedRangeCheck(): if we know that X != 0, handle more cases (PR43246) 
Summary:
This is motivated by D67122 sanitizer check enhancement.
That patch seemingly worsens `-fsanitize=pointer-overflow`
overhead from 25% to 50%, which strongly implies missing folds.

In this particular case, given
```
char* test(char& base, unsigned long offset) {
  return &base + offset;
}
```
it will end up producing something like
https://godbolt.org/z/LK5-iH
which after optimizations reduces down to roughly
```
define i1 @t0(i8* nonnull %base, i64 %offset) {
  %base_int = ptrtoint i8* %base to i64
  %adjusted = add i64 %base_int, %offset
  %non_null_after_adjustment = icmp ne i64 %adjusted, 0
  %no_overflow_during_adjustment = icmp uge i64 %adjusted, %base_int
  %res = and i1 %non_null_after_adjustment, %no_overflow_during_adjustment
  ret i1 %res
}
```
Without D67122 there was no `%non_null_after_adjustment`,
and in this particular case we can get rid of the overhead:

Here we add some offset to a non-null pointer,
and check that the result does not overflow and is not a null pointer.
But since the base pointer is already non-null, and we check for overflow,
that overflow check will already catch the null pointer,
so the separate null check is redundant and can be dropped.

Alive proofs:
https://rise4fun.com/Alive/WRzq

There are more patterns of "unsigned-add-with-overflow", they are not handled here,
but this is the main pattern, that we currently consider canonical,
so it makes sense to handle it.

https://bugs.llvm.org/show_bug.cgi?id=43246

Reviewers: spatel, nikic, vsk

Reviewed By: spatel

Subscribers: hiraditya, llvm-commits, reames

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67332

llvm-svn: 371349
2019-09-08 20:14:15 +00:00
..
2010-12-20-Boolean.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
2011-01-14-Thread.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
2011-02-01-Vector.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
2011-09-05-InsertExtractValue.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
2011-10-27-BinOpCrash.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
2011-11-23-MaskedBitsCrash.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
2013-04-19-ConstantFoldingCrash.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
add-mask.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
add.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
addsub.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
and-icmps-same-ops.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
and-or-icmp-zero.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
AndOrXor.ll [InstSimplify] simplify power-of-2 (single bit set) sequences 2019-06-20 22:55:28 +00:00
assume.ll [InstSimplify] remove quadratic time looping (PR42771) 2019-07-27 14:05:51 +00:00
bitcast-vector-fold.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
bitreverse-fold.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
bitreverse.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
bswap.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
call.ll [InstSimplify] Fix addo/subo undef folds (PR42209) 2019-06-16 20:39:45 +00:00
cast-unsigned-icmp-cmp-0.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
cast.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
cmp_of_min_max.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
compare.ll [InstructionSimplify] Apply sext/trunc after pointer stripping 2019-07-16 01:03:06 +00:00
constantfold-add-nuw-allones-to-allones.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
constantfold-shl-nuw-C-to-C.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
dead-code-removal.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
div-by-0-guard-before-smul_ov-not.ll [InstSimplify] Drop leftover "division-by-zero guard" around @llvm.umul.with.overflow inverted overflow bit 2019-08-29 12:48:04 +00:00
div-by-0-guard-before-smul_ov.ll [InstSimplify] Drop leftover "division-by-zero guard" around @llvm.umul.with.overflow overflow bit 2019-08-29 12:47:50 +00:00
div-by-0-guard-before-umul_ov-not.ll [InstSimplify] Drop leftover "division-by-zero guard" around @llvm.umul.with.overflow inverted overflow bit 2019-08-29 12:48:04 +00:00
div-by-0-guard-before-umul_ov.ll [InstSimplify] Drop leftover "division-by-zero guard" around @llvm.umul.with.overflow overflow bit 2019-08-29 12:47:50 +00:00
div.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
exact-nsw-nuw.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
extract-element.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
fast-math.ll [InstSimplify] Add unary fneg to fsub 0.0, (fneg X) ==> X transform 2019-05-17 16:47:00 +00:00
fcmp-select.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
fdiv.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
floating-point-arithmetic.ll [InstSimplify] Teach fsub -0.0, (fneg X) ==> X about unary fneg 2019-05-20 13:13:35 +00:00
floating-point-compare.ll [InstSimplify] enhance fcmp fold with never-nan operand 2019-06-09 13:48:59 +00:00
fold-builtin-fma.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
fold-intrinsics.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
fp-nan.ll Revert llvm-svn: 360807 2019-05-15 20:48:50 +00:00
fp-undef.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
gep.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
icmp-abs-nabs.ll [ValueTracking] When calculating known bits for integer abs, make sure we're looking at a negate and not just any instruction with the nsw flag set. 2019-08-07 18:28:16 +00:00
icmp-bool-constant.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
icmp-constant.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
icmp-ranges.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
implies.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
insertelement.ll [InstSimplify] guard against unreachable code (PR43218) 2019-09-04 15:12:55 +00:00
known-never-nan.ll [NFC][InstSimplify] Precommit new unary fneg test 2019-05-17 18:34:35 +00:00
known-non-zero.ll Revert "[ValueTracking] Improve isKnowNonZero for Ints" 2019-05-08 14:50:01 +00:00
load-relative-32.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
load-relative.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
load.ll [ConstantFolding] Fix assertion failure on non-power-of-two vector load. 2019-06-19 10:28:48 +00:00
log2-pow2-intrinsic.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
log10-pow10-intrinsic.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
log-exp-intrinsic.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
logic-of-fcmps.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
maxmin.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
mul.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
negate.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
noalias-ptr.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
or-icmps-same-ops.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
or.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
past-the-end.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
phi.ll [InstSimplify] add a phi test with 1 incoming value; NFC 2019-06-19 17:23:29 +00:00
pr28725.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
pr33957.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
ptr_diff.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
reassociate.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
redundant-null-check-in-uadd_with_overflow-of-nonnull-ptr.ll [InstSimplify] simplifyUnsignedRangeCheck(): if we know that X != 0, handle more cases (PR43246) 2019-09-08 20:14:15 +00:00
rem.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
remove-dead-call.ll [InstSimplify] Report "Changed" also when only deleting dead instructions 2019-08-09 07:08:25 +00:00
require-dominator.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
returned.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
round-intrinsics.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
saturating-add-sub.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
sdiv.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
select-and-cmp.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
select-implied.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
select-or-cmp.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
select.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
shift-128-kb.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
shift-knownbits.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
shift.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
shr-nop.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
shr-scalar-vector-consistency.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
shufflevector.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
signed-div-rem.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
simplify-nested-bitcast.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
srem.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
sub.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
undef.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
vec-cmp.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
vector_gep.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00
vector_ptr_bitcast.ll Revert "Temporarily Revert "Add basic loop fusion pass."" 2019-04-17 04:52:47 +00:00