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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Erik Corry <erikcorry@chromium.org>
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Date: Wed, 26 Feb 2025 18:44:05 +0100
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Subject: Revert "heap: Add masm-specific unwinding annotations to GC
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This reverts commit 42bc7bfdf56cc7a8cd7757d96aa70b83ce82d9ff.
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This commit broke our build, because we patch V8 to build push_registers_asm.cc
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with clang-cl on Windows, and this commit makes it an error to compile that
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file on Windows with any compiler. Maybe clang-cl and masm can be used
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together? I'm not sure. In the meantime, I'm reverting this commit in the hope
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of getting our V8 upgrade unblocked.
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Signed-off-by: James M Snell <jsnell@cloudflare.com>
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diff --git a/BUILD.gn b/BUILD.gn
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index 382c7d3ed44eab5df1f33082d0d0ef85121bc47c..5d5320c956b322ac9beef18688c9faa0bb10477f 100644
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--- a/BUILD.gn
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+++ b/BUILD.gn
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@@ -4638,8 +4638,8 @@ v8_header_set("v8_internal_headers") {
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     "src/tasks/operations-barrier.h",
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     "src/tasks/task-utils.h",
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     "src/torque/runtime-macro-shims.h",
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-    "src/tracing/trace-event-no-perfetto.h",
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     "src/tracing/trace-event.h",
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+    "src/tracing/trace-event-no-perfetto.h",
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     "src/tracing/trace-id.h",
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     "src/tracing/traced-value.h",
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     "src/tracing/tracing-category-observer.h",
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@@ -7560,12 +7560,7 @@ v8_source_set("v8_heap_base") {
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   ]
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   if (current_cpu == "x64") {
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-    if (is_win) {
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-      # Prefer a masm version with unwind directives.
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-      sources += [ "src/heap/base/asm/x64/push_registers_masm.asm" ]
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-    } else {
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-      sources += [ "src/heap/base/asm/x64/push_registers_asm.cc" ]
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-    }
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+    sources += [ "src/heap/base/asm/x64/push_registers_asm.cc" ]
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   } else if (current_cpu == "x86") {
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     sources += [ "src/heap/base/asm/ia32/push_registers_asm.cc" ]
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   } else if (current_cpu == "arm") {
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diff --git a/src/heap/base/asm/x64/push_registers_asm.cc b/src/heap/base/asm/x64/push_registers_asm.cc
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index d1d79dcfd5a8fce8240d8981b25c8027e220b03b..3f17db19310ff64e9316d0bb8308e399f5ce1422 100644
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--- a/src/heap/base/asm/x64/push_registers_asm.cc
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+++ b/src/heap/base/asm/x64/push_registers_asm.cc
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@@ -14,16 +14,61 @@
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 // Do not depend on V8_TARGET_OS_* defines as some embedders may override the
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 // GN toolchain (e.g. ChromeOS) and not provide them.
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+// _WIN64 Defined as 1 when the compilation target is 64-bit ARM or x64.
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+// Otherwise, undefined.
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+#ifdef _WIN64
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 // We maintain 16-byte alignment at calls. There is an 8-byte return address
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-// on the stack and we push 56 bytes which maintains 16-byte stack alignment
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+// on the stack and we push 232 bytes which maintains 16-byte stack alignment
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 // at the call.
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-// Source: https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-1.0.pdf
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+// Source: https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention
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+asm(".att_syntax                                        \n"
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+    ".globl PushAllRegistersAndIterateStack             \n"
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+    "PushAllRegistersAndIterateStack:                   \n"
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+    // rbp is callee-saved. Maintain proper frame pointer for debugging.
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+    "  push %rbp                                        \n"
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+    "  mov %rsp, %rbp                                   \n"
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+    // Dummy for alignment.
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+    "  push $0xCDCDCD                                   \n"
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+    "  push %rsi                                        \n"
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+    "  push %rdi                                        \n"
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+    "  push %rbx                                        \n"
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+    "  push %r12                                        \n"
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+    "  push %r13                                        \n"
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+    "  push %r14                                        \n"
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+    "  push %r15                                        \n"
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+    "  sub $160, %rsp                                   \n"
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+    // Use aligned instrs as we are certain that the stack is properly aligned.
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+    "  movdqa %xmm6, 144(%rsp)                          \n"
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+    "  movdqa %xmm7, 128(%rsp)                          \n"
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+    "  movdqa %xmm8, 112(%rsp)                          \n"
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+    "  movdqa %xmm9, 96(%rsp)                           \n"
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+    "  movdqa %xmm10, 80(%rsp)                          \n"
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+    "  movdqa %xmm11, 64(%rsp)                          \n"
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+    "  movdqa %xmm12, 48(%rsp)                          \n"
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+    "  movdqa %xmm13, 32(%rsp)                          \n"
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+    "  movdqa %xmm14, 16(%rsp)                          \n"
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+    "  movdqa %xmm15, (%rsp)                            \n"
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+    // Pass 1st parameter (rcx) unchanged (Stack*).
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+    // Pass 2nd parameter (rdx) unchanged (StackVisitor*).
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+    // Save 3rd parameter (r8; IterateStackCallback)
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+    "  mov %r8, %r9                                     \n"
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+    // Pass 3rd parameter as rsp (stack pointer).
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+    "  mov %rsp, %r8                                    \n"
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+    // Call the callback.
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+    "  call *%r9                                        \n"
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+    // Pop the callee-saved registers.
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+    "  add $224, %rsp                                   \n"
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+    // Restore rbp as it was used as frame pointer.
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+    "  pop %rbp                                         \n"
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+    "  ret                                              \n");
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-#ifdef _WIN64
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-#error "The masm based version must be used for Windows"
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-#endif
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+#else  // !_WIN64
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+// We maintain 16-byte alignment at calls. There is an 8-byte return address
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+// on the stack and we push 56 bytes which maintains 16-byte stack alignment
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+// at the call.
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+// Source: https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-1.0.pdf
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 asm(
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 #ifdef __APPLE__
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     ".globl _PushAllRegistersAndIterateStack            \n"
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@@ -81,3 +126,5 @@ asm(
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     ".Lfunc_end0-PushAllRegistersAndIterateStack        \n"
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 #endif  // !defined(__APPLE__)
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     ".cfi_endproc                                      \n");
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+
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+#endif  // !_WIN64
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diff --git a/src/heap/base/asm/x64/push_registers_masm.asm b/src/heap/base/asm/x64/push_registers_masm.asm
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index d0d05632d26883316cb7b39f8e7e8143d2b24bc3..a32e193c2f132cdbe1d0730831d8659be996f8e2 100644
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--- a/src/heap/base/asm/x64/push_registers_masm.asm
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+++ b/src/heap/base/asm/x64/push_registers_masm.asm
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@@ -8,7 +8,7 @@
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 public PushAllRegistersAndIterateStack
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 .code
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-PushAllRegistersAndIterateStack proc frame
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+PushAllRegistersAndIterateStack:
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     ;; Push all callee-saved registers to get them on the stack for conservative
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     ;; stack scanning.
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     ;;
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@@ -19,28 +19,16 @@ PushAllRegistersAndIterateStack proc frame
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     ;;
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     ;; rbp is callee-saved. Maintain proper frame pointer for debugging.
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     push rbp
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-    .pushreg rbp
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     mov rbp, rsp
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-    .setframe rbp, 0
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     push 0CDCDCDh  ;; Dummy for alignment.
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-    .allocstack 8
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     push rsi
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-    .pushreg rsi
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     push rdi
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-    .pushreg rdi
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     push rbx
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-    .pushreg rbx
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     push r12
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-    .pushreg r12
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     push r13
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-    .pushreg r13
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     push r14
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-    .pushreg r14
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     push r15
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-    .pushreg r15
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     sub rsp, 160
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-    .allocstack 160
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-    .endprolog
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     ;; Use aligned instrs as we are certain that the stack is properly aligned.
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     movdqa  xmmword ptr [rsp + 144], xmm6
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     movdqa  xmmword ptr [rsp + 128], xmm7
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@@ -65,6 +53,5 @@ PushAllRegistersAndIterateStack proc frame
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     ;; Restore rbp as it was used as frame pointer.
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     pop rbp
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     ret
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-    PushAllRegistersAndIterateStack endp
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 end