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Investigate use of IR-based counter instrumentation for coverage #32847

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vedantk opened this issue Jun 18, 2017 · 4 comments
Open

Investigate use of IR-based counter instrumentation for coverage #32847

vedantk opened this issue Jun 18, 2017 · 4 comments
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bugzilla Issues migrated from bugzilla clang:codegen

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@vedantk
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vedantk commented Jun 18, 2017

Bugzilla Link 33500
Version trunk
OS All

Extended Description

Coverage makes use of frontend-based PGO instrumentation, which is much less efficient than the IR-based kind, primarily because it has no visibility into LLVM's inlining decisions. This results in instrumented basic blocks which contain multiple (redundant) counter increments. If we can find a way to map counters inserted by IR PGO to AST nodes, we could improve the situation.
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vedantk commented Jun 18, 2017

assigned to @vedantk

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llvmbot commented Jun 20, 2017

It seems to be doable: FE needs to create and pass the mapping from regions to basic blocks to LLVM in some way so that the IR PGO can use the information to update the counter expressions associated with source regions.

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mentioned in issue llvm/llvm-bugzilla-archive#34533

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kcc commented Nov 26, 2021

mentioned in issue llvm/llvm-bugzilla-archive#34533

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 10, 2021
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