For global function merging, the target of the arc-attached call must be a constant and cannot be parameterized. This change adds a check to bypass this case in `canParameterizeCallOperand()`.
This update follows up on change #112671 and is mostly a NFC, with the following exceptions: - Introduced `-global-merging-skip-no-params` to bypass merging when no parameters are required. - Parameter count is now calculated based on the unique hash count. - Added `-global-merging-inst-overhead` to adjust the instruction overhead, reflecting the machine instruction size. - Costs and benefits are now computed using the double data type. Since the finalization process occurs offline, this should not significantly impact build time. - Moved a sorting operation outside of the loop. This is a patch for https://discourse.llvm.org/t/rfc-global-function-merging/82608.
This reverts commit fdf1f69c57ac3667d27c35e097040284edb1f574.
This update follows up on change #112671 and is mostly a NFC, with the following exceptions: - Introduced `-global-merging-skip-no-params` to bypass merging when no parameters are required. - Parameter count is now calculated based on the unique hash count. - Added `-global-merging-inst-overhead` to adjust the instruction overhead, reflecting the machine instruction size. - Costs and benefits are now computed using the double data type. Since the finalization process occurs offline, this should not significantly impact build time. - Moved a sorting operation outside of the loop. This is a patch for https://discourse.llvm.org/t/rfc-global-function-merging/82608.
Module summary index is optional for this pass, and we shouldn't run it, but import it as necessary.
This is a follow-up PR to refactor the initial global merge function pass implemented in #112671. It first collects stable functions relevant to the current module and iterates over those only, instead of iterating through all stable functions in the stable function map. This is a patch for https://discourse.llvm.org/t/rfc-global-function-merging/82608.
This reverts commit d3da78863c7021fa2447a168dc03ad791db69dc6.
This is a follow-up PR to refactor the initial global merge function pass implemented in #112671. It first collects stable functions relevant to the current module and iterates over those only, instead of iterating through all stable functions in the stable function map. This is a patch for https://discourse.llvm.org/t/rfc-global-function-merging/82608.
This implements a global function merging pass. Unlike traditional function merging passes that use IR comparators, this pass employs a structurally stable hash to identify similar functions while ignoring certain constant operands. These ignored constants are tracked and encoded into a stable function summary. When merging, instead of explicitly folding similar functions and their call sites, we form a merging instance by supplying different parameters via thunks. The actual size reduction occurs when identically created merging instances are folded by the linker. Currently, this pass is wired to a pre-codegen pass, enabled by the `-enable-global-merge-func` flag. In a local merging mode, the analysis and merging steps occur sequentially within a module: - `analyze`: Collects stable function hashes and tracks locations of ignored constant operands. - `finalize`: Identifies merge candidates with matching hashes and computes the set of parameters that point to different constants. - `merge`: Uses the stable function map to optimistically create a merged function. We can enable a global merging mode similar to the global function outliner (https://discourse.llvm.org/t/rfc-enhanced-machine-outliner-part-2-thinlto-nolto/78753/), which will perform the above steps separately. - `-codegen-data-generate`: During the first round of code generation, we analyze local merging instances and publish their summaries. - Offline using `llvm-cgdata` or at link-time, we can finalize all these merging summaries that are combined to determine parameters. - `-codegen-data-use`: During the second round of code generation, we optimistically create merging instances within each module, and finally, the linker folds identically created merging instances. Depends on #112664 This is a patch for https://discourse.llvm.org/t/rfc-global-function-merging/82608.