[CIR][CodeGen] emit cir.zero for constant string literals #373

Lancern · 2023-12-30T04:45:30Z

This PR addresses #248 .

Currently string literals are always lowered to a cir.const_array attribute even if the string literal only contains null bytes. This patch make the CodeGen emits cir.zero for these string literals.

Currently string literals are always lowered to a cir.const_array attribute even if the string literal only contains null bytes. This patch make the CodeGen emits cir.zero for these string literals.

sitio-couto

Looks good. Just a minor suggestion.

clang/lib/CIR/CodeGen/CIRGenModule.cpp

This PR addresses #248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

This PR addresses llvm#248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

This PR addresses #248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

This PR addresses llvm#248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

This PR addresses #248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

The patch resolves [issue llvm#248](llvm#248). It can be considered a subsequent patch to [llvm#373](llvm#373), where the case of empty strings was processed. The new patch adds processing for non-empty strings that may contain trailing zeros, such as: ``` char big_string[100000] = "123"; ``` That is converted to ``` @big_string = #cir.const_array<"123" : !cir.array<!s8i x 3>, trailing_zeros> : !cir.array<!s8i x 100000> ``` It's worth noting that ordinary strings that are terminated with a single zero also get the trailing zeros, for instance ``` char string[] = "whatnow"; ``` Is converted to ``` @string = #cir.const_array<"whatnow" : !cir.array<!s8i x 7>, trailing_zeros> : !cir.array<!s8i x 8> ```

) The patch resolves [issue #248](#248). It can be considered a subsequent patch to [#373](#373), where the case of empty strings was processed. The new patch adds processing for non-empty strings that may contain trailing zeros, such as: ``` char big_string[100000] = "123"; ``` That is converted to ``` @big_string = #cir.const_array<"123" : !cir.array<!s8i x 3>, trailing_zeros> : !cir.array<!s8i x 100000> ```

…lvm#617) The patch resolves [issue llvm#248](llvm/clangir#248). It can be considered a subsequent patch to [llvm#373](llvm/clangir#373), where the case of empty strings was processed. The new patch adds processing for non-empty strings that may contain trailing zeros, such as: ``` char big_string[100000] = "123"; ``` That is converted to ``` @big_string = #cir.const_array<"123" : !cir.array<!s8i x 3>, trailing_zeros> : !cir.array<!s8i x 100000> ```

This PR addresses llvm#248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

…lvm#617) The patch resolves [issue llvm#248](llvm#248). It can be considered a subsequent patch to [llvm#373](llvm#373), where the case of empty strings was processed. The new patch adds processing for non-empty strings that may contain trailing zeros, such as: ``` char big_string[100000] = "123"; ``` That is converted to ``` @big_string = #cir.const_array<"123" : !cir.array<!s8i x 3>, trailing_zeros> : !cir.array<!s8i x 100000> ```

This PR addresses llvm#248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

…lvm#617) The patch resolves [issue llvm#248](llvm#248). It can be considered a subsequent patch to [llvm#373](llvm#373), where the case of empty strings was processed. The new patch adds processing for non-empty strings that may contain trailing zeros, such as: ``` char big_string[100000] = "123"; ``` That is converted to ``` @big_string = #cir.const_array<"123" : !cir.array<!s8i x 3>, trailing_zeros> : !cir.array<!s8i x 100000> ```

This PR addresses #248 . Currently string literals are always lowered to a `cir.const_array` attribute even if the string literal only contains null bytes. This patch make the CodeGen emits `cir.zero` for these string literals.

) The patch resolves [issue #248](#248). It can be considered a subsequent patch to [#373](#373), where the case of empty strings was processed. The new patch adds processing for non-empty strings that may contain trailing zeros, such as: ``` char big_string[100000] = "123"; ``` That is converted to ``` @big_string = #cir.const_array<"123" : !cir.array<!s8i x 3>, trailing_zeros> : !cir.array<!s8i x 100000> ```

Lancern added 2 commits December 30, 2023 12:42

[CIR] emit cir.zero for constant string literals

f04edff

Currently string literals are always lowered to a cir.const_array attribute even if the string literal only contains null bytes. This patch make the CodeGen emits cir.zero for these string literals.

Generate cir.zero within builder.getString

c178379

sitio-couto reviewed Jan 4, 2024

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clang/lib/CIR/CodeGen/CIRGenModule.cpp Outdated Show resolved Hide resolved

bcardosolopes approved these changes Jan 4, 2024

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bcardosolopes merged commit c5e1756 into llvm:main Jan 4, 2024
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Lancern deleted the cir-zero-in-const-str branch January 5, 2024 13:39

ivanmurashko mentioned this pull request May 19, 2024

[CIR][CodeGen] Support trailing_zeros for constant string literals #617

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[CIR][CodeGen] emit cir.zero for constant string literals #373

[CIR][CodeGen] emit cir.zero for constant string literals #373

Lancern commented Dec 30, 2023

sitio-couto left a comment

[CIR][CodeGen] emit cir.zero for constant string literals #373

[CIR][CodeGen] emit cir.zero for constant string literals #373

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Lancern commented Dec 30, 2023

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