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* Revert "Temporarily Revert "Add basic loop fusion pass.""Eric Christopher2019-04-171-0/+121
| | | | | | | | The reversion apparently deleted the test/Transforms directory. Will be re-reverting again. llvm-svn: 358552
* Temporarily Revert "Add basic loop fusion pass."Eric Christopher2019-04-171-121/+0
| | | | | | | | As it's causing some bot failures (and per request from kbarton). This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda. llvm-svn: 358546
* Use branch funnels for virtual calls when retpoline mitigation is enabled.Peter Collingbourne2018-03-091-12/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The retpoline mitigation for variant 2 of CVE-2017-5715 inhibits the branch predictor, and as a result it can lead to a measurable loss of performance. We can reduce the performance impact of retpolined virtual calls by replacing them with a special construct known as a branch funnel, which is an instruction sequence that implements virtual calls to a set of known targets using a binary tree of direct branches. This allows the processor to speculately execute valid implementations of the virtual function without allowing for speculative execution of of calls to arbitrary addresses. This patch extends the whole-program devirtualization pass to replace certain virtual calls with calls to branch funnels, which are represented using a new llvm.icall.jumptable intrinsic. It also extends the LowerTypeTests pass to recognize the new intrinsic, generate code for the branch funnels (x86_64 only for now) and lay out virtual tables as required for each branch funnel. The implementation supports full LTO as well as ThinLTO, and extends the ThinLTO summary format used for whole-program devirtualization to support branch funnels. For more details see RFC: http://lists.llvm.org/pipermail/llvm-dev/2018-January/120672.html Differential Revision: https://reviews.llvm.org/D42453 llvm-svn: 327163
* WholeProgramDevirt: Add import/export support for targets without absolute ↵Peter Collingbourne2017-09-111-9/+13
| | | | | | | | | | | | | | | | | | | symbol constants. Not all targets support the use of absolute symbols to export constants. In particular, ARM has a wide variety of constant encodings that cannot currently be relocated by linkers. So instead of exporting the constants using symbols, export them directly in the summary. The values of the constants are left as zeroes on targets that support symbolic exports. This may result in more cache misses when targeting those architectures as a result of arbitrary changes in constant values, but this seems somewhat unavoidable for now. Differential Revision: https://reviews.llvm.org/D37407 llvm-svn: 312967
* WholeProgramDevirt: Create bitcast to i8* at each virtual call site.Peter Collingbourne2017-08-221-0/+1
| | | | | | | | | We can't reuse the llvm.assume instruction's bitcast because it may not dominate every user of the vtable pointer. Differential Revision: https://reviews.llvm.org/D36994 llvm-svn: 311491
* WholeProgramDevirt: Implement export/import support for VCP.Peter Collingbourne2017-03-101-0/+24
| | | | | | Differential Revision: https://reviews.llvm.org/D30017 llvm-svn: 297503
* WholeProgramDevirt: Implement export/import support for unique ret val opt.Peter Collingbourne2017-03-101-0/+26
| | | | | | Differential Revision: https://reviews.llvm.org/D29917 llvm-svn: 297502
* WholeProgramDevirt: Implement importing for uniform ret val opt.Peter Collingbourne2017-03-091-0/+9
| | | | | | Differential Revision: https://reviews.llvm.org/D29854 llvm-svn: 297350
* WholeProgramDevirt: Implement importing for single-impl devirtualization.Peter Collingbourne2017-03-091-0/+49
Differential Revision: https://reviews.llvm.org/D29844 llvm-svn: 297333
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