c5b15c2396
Add a calling-convention setting to the `Flags` used as part of the `TargetIsa`. This allows Cretonne code that generates calls to use the correct convention, such as when emitting libcalls during legalization or when the wasm frontend is decoding functions. This setting can be overridden per-function. This also adds "fast", "cold", and "fastcall" conventions, with "fast" as the new default. Note that "fast" and "cold" are not intended to be ABI-compatible across Cretonne versions. This will also ensure Windows users will get an `unimplemented!` rather than silent calling-convention mismatches, which reflects the fact that Windows calling conventions are not yet implemented. This also renames SpiderWASM, which isn't camel-case, to Baldrdash, which is, and which is also a more relevant name.
119 lines
3.9 KiB
Python
119 lines
3.9 KiB
Python
"""
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Cretonne shared settings.
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This module defines settings relevant for all code generators.
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"""
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from __future__ import absolute_import
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from cdsl.settings import SettingGroup, BoolSetting, EnumSetting, NumSetting
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group = SettingGroup('shared')
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opt_level = EnumSetting(
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"""
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Optimization level:
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- default: Very profitable optimizations enabled, none slow.
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- best: Enable all optimizations
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- fastest: Optimize for compile time by disabling most optimizations.
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""",
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'default', 'best', 'fastest')
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enable_verifier = BoolSetting(
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"""
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Run the Cretonne IR verifier at strategic times during compilation.
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This makes compilation slower but catches many bugs. The verifier is
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disabled by default, except when reading Cretonne IR from a text file.
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""",
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default=True)
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is_64bit = BoolSetting("Enable 64-bit code generation")
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call_conv = EnumSetting(
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"""
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Default calling convention:
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- fast: not-ABI-stable convention for best performance
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- cold: not-ABI-stable convention for infrequently executed code
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- system_v: System V-style convention used on many platforms
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- fastcall: Windows "fastcall" convention, also used for x64 and ARM
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- baldrdash: SpiderMonkey WebAssembly convention
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The default calling convention may be overridden by individual
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functions.
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""",
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'fast', 'cold', 'system_v', 'fastcall', 'baldrdash')
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# Note that Cretonne doesn't currently need an is_pie flag, because PIE is just
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# PIC where symbols can't be pre-empted, which can be expressed with the
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# `colocated` flag on external functions and global variables.
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is_pic = BoolSetting("Enable Position-Independent Code generation")
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return_at_end = BoolSetting(
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"""
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Generate functions with at most a single return instruction at the
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end of the function.
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This guarantees that functions do not have any internal return
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instructions. Either they never return, or they have a single return
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instruction at the end.
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""")
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avoid_div_traps = BoolSetting(
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"""
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Generate explicit checks around native division instructions to avoid
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their trapping.
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This is primarily used by SpiderMonkey which doesn't install a signal
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handler for SIGFPE, but expects a SIGILL trap for division by zero.
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On ISAs like ARM where the native division instructions don't trap,
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this setting has no effect - explicit checks are always inserted.
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""")
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is_compressed = BoolSetting("Enable compressed instructions")
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enable_float = BoolSetting(
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"""
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Enable the use of floating-point instructions
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Disabling use of floating-point instructions is not yet implemented.
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""",
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default=True)
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enable_simd = BoolSetting(
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"""Enable the use of SIMD instructions.""",
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default=True)
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enable_atomics = BoolSetting(
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"""Enable the use of atomic instructions""",
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default=True)
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#
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# Settings specific to the `baldrdash` calling convention.
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#
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baldrdash_prologue_words = NumSetting(
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"""
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Number of pointer-sized words pushed by the baldrdash prologue.
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Functions with the `baldrdash` calling convention don't generate their
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own prologue and epilogue. They depend on externally generated code
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that pushes a fixed number of words in the prologue and restores them
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in the epilogue.
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This setting configures the number of pointer-sized words pushed on the
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stack when the Cretonne-generated code is entered. This includes the
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pushed return address on x86.
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""")
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#
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# BaldrMonkey requires that not-yet-relocated function addresses be encoded
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# as all-ones bitpatterns.
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#
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allones_funcaddrs = BoolSetting(
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"""
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Emit not-yet-relocated function addresses as all-ones bit patterns.
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""")
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group.close(globals())
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