summaryrefslogtreecommitdiffstats
path: root/llvm/test/Transforms/InstCombine/signed-truncation-check.ll
Commit message (Collapse)AuthorAgeFilesLines
* Revert "Temporarily Revert "Add basic loop fusion pass.""Eric Christopher2019-04-171-0/+621
| | | | | | | | The reversion apparently deleted the test/Transforms directory. Will be re-reverting again. llvm-svn: 358552
* Temporarily Revert "Add basic loop fusion pass."Eric Christopher2019-04-171-621/+0
| | | | | | | | As it's causing some bot failures (and per request from kbarton). This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda. llvm-svn: 358546
* [InstCombine] Re-land: Optimize redundant 'signed truncation check pattern'.Roman Lebedev2018-08-131-57/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This comes with `Implicit Conversion Sanitizer - integer sign change` (D50250): ``` signed char test(unsigned int x) { return x; } ``` `clang++ -fsanitize=implicit-conversion -S -emit-llvm -o - /tmp/test.cpp -O3` * Old: {F6904292} * With this patch: {F6904294} General pattern: X & Y Where `Y` is checking that all the high bits (covered by a mask `4294967168`) are uniform, i.e. `%arg & 4294967168` can be either `4294967168` or `0` Pattern can be one of: %t = add i32 %arg, 128 %r = icmp ult i32 %t, 256 Or %t0 = shl i32 %arg, 24 %t1 = ashr i32 %t0, 24 %r = icmp eq i32 %t1, %arg Or %t0 = trunc i32 %arg to i8 %t1 = sext i8 %t0 to i32 %r = icmp eq i32 %t1, %arg This pattern is a signed truncation check. And `X` is checking that some bit in that same mask is zero. I.e. can be one of: %r = icmp sgt i32 %arg, -1 Or %t = and i32 %arg, 2147483648 %r = icmp eq i32 %t, 0 Since we are checking that all the bits in that mask are the same, and a particular bit is zero, what we are really checking is that all the masked bits are zero. So this should be transformed to: %r = icmp ult i32 %arg, 128 The transform itself ended up being rather horrible, even though i omitted some cases. Surely there is some infrastructure that can help clean this up that i missed? https://rise4fun.com/Alive/3Ou The initial commit (rL339610) was reverted, since the first assert was being triggered. The @positive_with_extra_and test now has coverage for that case. Reviewers: spatel, craig.topper Reviewed By: spatel Subscribers: RKSimon, erichkeane, vsk, llvm-commits Differential Revision: https://reviews.llvm.org/D50465 llvm-svn: 339621
* [NFC][InstCombine] Add a test for D50465 that used to assertRoman Lebedev2018-08-131-0/+19
| | | | | | | This is valid to fold, too. https://rise4fun.com/Alive/0lz llvm-svn: 339619
* Revert "[InstCombine] Optimize redundant 'signed truncation check pattern'."Roman Lebedev2018-08-131-22/+51
| | | | | | | | | At least one buildbot was able to actually trigger that assert on the top of the function. Will investigate. This reverts commit r339610. llvm-svn: 339612
* [InstCombine] Optimize redundant 'signed truncation check pattern'.Roman Lebedev2018-08-131-51/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This comes with `Implicit Conversion Sanitizer - integer sign change` (D50250): ``` signed char test(unsigned int x) { return x; } ``` `clang++ -fsanitize=implicit-conversion -S -emit-llvm -o - /tmp/test.cpp -O3` * Old: {F6904292} * With this patch: {F6904294} General pattern: X & Y Where `Y` is checking that all the high bits (covered by a mask `4294967168`) are uniform, i.e. `%arg & 4294967168` can be either `4294967168` or `0` Pattern can be one of: %t = add i32 %arg, 128 %r = icmp ult i32 %t, 256 Or %t0 = shl i32 %arg, 24 %t1 = ashr i32 %t0, 24 %r = icmp eq i32 %t1, %arg Or %t0 = trunc i32 %arg to i8 %t1 = sext i8 %t0 to i32 %r = icmp eq i32 %t1, %arg This pattern is a signed truncation check. And `X` is checking that some bit in that same mask is zero. I.e. can be one of: %r = icmp sgt i32 %arg, -1 Or %t = and i32 %arg, 2147483648 %r = icmp eq i32 %t, 0 Since we are checking that all the bits in that mask are the same, and a particular bit is zero, what we are really checking is that all the masked bits are zero. So this should be transformed to: %r = icmp ult i32 %arg, 128 https://rise4fun.com/Alive/3Ou Reviewers: spatel, craig.topper Reviewed By: spatel Subscribers: RKSimon, erichkeane, vsk, llvm-commits Differential Revision: https://reviews.llvm.org/D50465 llvm-svn: 339610
* [InstCombine][NFC] Tests for 'signed truncation check' optimizationRoman Lebedev2018-08-131-0/+634
See D50465 for the actual opt itself. Differential Revision: https://reviews.llvm.org/D50464 llvm-svn: 339602
OpenPOWER on IntegriCloud