feat(rtl): migrate blaise_start .s to inline asm
This commit is contained in:
Graeme Geldenhuys
parent
7781242696
commit
d840f40e89
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@ -41,12 +41,12 @@ BLAISE = $(COMPILER_BIN)/blaise
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BLAISE_FLAGS = --no-incremental --assembler internal
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# Assembly sources — platform-specific, no C compiler needed.
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# (blaise_atomic, blaise_setjmp migrated to inline-asm Pascal units.)
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ASM_OBJS = $(OBJ_DIR)/blaise_start_x86_64.o \
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$(OBJ_DIR)/blaise_utf8_x86_64.o
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# (blaise_atomic, blaise_setjmp, blaise_start migrated to inline-asm units.)
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ASM_OBJS = $(OBJ_DIR)/blaise_utf8_x86_64.o
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# Pascal RTL units compiled via the Blaise compiler.
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PAS_OBJS = $(OBJ_DIR)/blaise_atomic.o \
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PAS_OBJS = $(OBJ_DIR)/blaise_start.o \
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$(OBJ_DIR)/blaise_atomic.o \
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$(OBJ_DIR)/blaise_setjmp.o \
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$(OBJ_DIR)/blaise_mem.o \
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$(OBJ_DIR)/blaise_str.o \
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@ -74,6 +74,10 @@ $(OBJ_DIR)/%.o: $(ASM_DIR)/%.s
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$(CC) -c -o $@ $<
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# --- Pascal unit rules (unit-as-top-level) ---
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$(OBJ_DIR)/blaise_start.o: $(PAS_SRC_DIR)/blaise_start.pas
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@mkdir -p $(OBJ_DIR)
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$(BLAISE) $(BLAISE_FLAGS) --source $< --unit-path $(PAS_SRC_DIR) --output $@
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$(OBJ_DIR)/blaise_atomic.o: $(PAS_SRC_DIR)/blaise_atomic.pas
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@mkdir -p $(OBJ_DIR)
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$(BLAISE) $(BLAISE_FLAGS) --source $< --unit-path $(PAS_SRC_DIR) --output $@
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@ -1,53 +0,0 @@
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#
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# Blaise — An Object Pascal Compiler
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# Copyright (c) 2026 Graeme Geldenhuys
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# SPDX-License-Identifier: Apache-2.0 WITH Swift-exception
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# Licensed under the Apache License v2.0 with Runtime Library Exception.
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# See LICENSE file in the project root for full license terms.
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#
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# Program entry point (x86_64, System V ABI, glibc-compatible).
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#
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# This replaces the system Scrt1.o so the internal linker needs no
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# gcc-provided startup object and no versioned gcc directory (issue #142).
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# The runtime ships its own _start; the linker (TLinker.Link '_start') uses
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# this symbol as the ELF entry point.
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#
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# On entry the kernel hands us the initial process stack:
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# (%rsp) argc
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# 8(%rsp) argv[0]
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# ... argv[argc] = NULL, then envp, then the auxiliary vector
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# and %rdx holds the dynamic linker's finaliser (rtld_fini) for PIE images.
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#
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# We marshal these into the arguments __libc_start_main expects:
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# __libc_start_main(main, argc, argv, init, fini, rtld_fini, stack_end)
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# %rdi = main (the program's C-style entry)
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# %rsi = argc
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# %rdx = argv
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# %rcx = init = NULL (unit init runs from main, not .init_array)
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# %r8 = fini = NULL
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# %r9 = rtld_fini
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# stack_end pushed on the stack
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# glibc runs the init array (if any), calls main(argc, argv, envp), then
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# exit(main's return value). This mirrors modern glibc's own Scrt1.o.
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.text
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.globl _start
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.type _start, @function
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_start:
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endbr64
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xor %ebp, %ebp # outermost frame marker (ABI)
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mov %rdx, %r9 # rtld_fini -> arg 7
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pop %rsi # argc -> arg 2
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mov %rsp, %rdx # argv -> arg 3 (now at stack top)
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and $0xfffffffffffffff0, %rsp # re-align stack to 16 bytes
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push %rax # padding (8 bytes) ...
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push %rsp # ... and stack_end, keeping alignment
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xor %r8d, %r8d # fini = NULL -> arg 5
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xor %ecx, %ecx # init = NULL -> arg 4
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lea main(%rip), %rdi # main -> arg 1
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call __libc_start_main@PLT # does not return
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hlt # trap if it ever does
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.size _start, .-_start
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.section .note.GNU-stack,"",@progbits
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52
runtime/src/main/pascal/blaise_start.pas
Normal file
52
runtime/src/main/pascal/blaise_start.pas
Normal file
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@ -0,0 +1,52 @@
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{
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Blaise - An Object Pascal Compiler
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Copyright (c) 2026 Graeme Geldenhuys
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SPDX-License-Identifier: Apache-2.0 WITH Swift-exception
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Licensed under the Apache License v2.0 with Runtime Library Exception.
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See LICENSE file in the project root for full license terms.
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}
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unit blaise_start;
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// Program entry point (x86_64, System V ABI, glibc-compatible).
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//
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// Inline-assembler port of runtime/src/main/asm/blaise_start_x86_64.s — _start
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// is now an `asm … end` routine so the RTL needs no hand-written .s
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// (docs/inline-asm-design.adoc, §"Migration of the .s files").
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//
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// This replaces the system Scrt1.o so the internal linker needs no
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// gcc-provided startup object (issue #142). The linker uses '_start' as the
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// ELF entry point; an unmangled unit-level routine named _start emits exactly
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// that symbol.
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//
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// On entry the kernel hands us the initial process stack:
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// (%rsp) argc 8(%rsp) argv[0] ... then NULL, envp, auxv
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// and %rdx holds rtld_fini for PIE images. We marshal these into the args
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// __libc_start_main(main, argc, argv, init=NULL, fini=NULL, rtld_fini,
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// stack_end) expects; glibc runs the init array, calls main(argc, argv, envp),
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// then exit(main's return). nostackframe: the body owns the whole frame.
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interface
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procedure _start;
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implementation
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procedure _start; assembler; nostackframe;
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asm
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endbr64
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xor %ebp, %ebp
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mov %rdx, %r9
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pop %rsi
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mov %rsp, %rdx
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and $0xfffffffffffffff0, %rsp
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push %rax
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push %rsp
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xor %r8d, %r8d
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xor %ecx, %ecx
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lea main(%rip), %rdi
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call __libc_start_main@PLT
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hlt
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end;
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end.
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