Change Details

The insertReplacementDbgValues utility helps optimization passes preserve debug info when replacing a to-be-DCE'd value with a new value. This patch simplifies the API by moving the responsibiliy for rewriting dbg.value DIExpressions from individual passes into common utility code. This should make the API easier to adopt, and allows generically useful improvements to be made to the expression rewriting logic. Along with the API change, this patch teaches insertReplacementDbgValues how to create DIExpressions for basic integer and pointer conversions: - The no-op conversion. Applies when the values have the same width, or have bit-for-bit compatible pointer representations. - Truncation. Applies when the new value is wider than the old one. - Zero/sign extension. Applies when the new value is narrower than the old one. Testing: - check-llvm, check-clang, a stage2 `-g -O3` build of clang, and added regression tests. - This resolves a number of mis-sized dbg.value diagnostics from Debugify.

The replaceAllDbgUsesWith utility helps passes preserve debug info when replacing one value with another. This improves upon the existing insertReplacementDbgValues API by: - Updating debug intrinsics in-place, while preventing use-before-def of the replacement value. - Falling back to salvageDebugInfo when a replacement can't be made. - Moving the responsibiliy for rewriting llvm.dbg.* DIExpressions into common utility code. Along with the API change, this teaches replaceAllDbgUsesWith how to create DIExpressions for three basic integer and pointer conversions: - The no-op conversion. Applies when the values have the same width, or have bit-for-bit compatible pointer representations. - Truncation. Applies when the new value is wider than the old one. - Zero/sign extension. Applies when the new value is narrower than the old one. Testing: - check-llvm, check-clang, a stage2 `-g -O3` build of clang, regression/unit testing. - This resolves a number of mis-sized dbg.value diagnostics from Debugify.

The insertRreplacementDbgValuesAllDbgUsesWith utility helps optimization passespasses preserve debug info when preserve debug info when replacing a to-be-DCE'done value with a new valuenother. This patch simplifies the API by moving the responsibiliy for rewritingimproves upon the existing insertReplacementDbgValues API by: - Updating debug intrinsics in-place, while preventing use-before-def of the replacement value. dbg.value DIExpressions from individual passes into common utility code- Falling back to salvageDebugInfo when a replacement can't be made. This should make- Moving the API easier to adopt, and allows generically usefulresponsibiliy for rewriting llvm.dbg.* DIExpressions into improvements to be made to the expression rewriting logic common utility code. Along with the API change, this patch teaches insertRreplacementDbgValuesAllDbgUsesWith how to how to create DIExpressions forr three basic integer and pointer conversions: - The no-op conversion. Applies when the values have the same width, or have bit-for-bit compatible pointer representations. - Truncation. Applies when the new value is wider than the old one. - Zero/sign extension. Applies when the new value is narrower than the old one. Testing: - check-llvm, check-clang, a stage2 `-g -O3` build of clang, and added regression/unit tests. ing. - This resolves a number of mis-sized dbg.value diagnostics from Debugify.