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Revert "cppgc: Fix test IteratePointersFindsCalleeSavedRegisters"

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This reverts commit 4ff37d3a3f.

Reason for revert: Fails with stress_incremental_marking - https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20TSAN%20-%20stress-incremental-marking/3049/blamelist

Original change's description:
> cppgc: Fix test IteratePointersFindsCalleeSavedRegisters
>
> call the compiler can clobber the tested register. Moving this tricky
> part into a noninlinable lambda allows to reduce pressure from the
> register allocator and thereby avoid such clobbering.
>
> Subtle: between the first inline assembly and the IteratePointers()
> Change-Id: Ibeca8fa2f4fd54d07c2f585a4e876504a6a991b7
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2859843
> Commit-Queue: Anton Bikineev <bikineev@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74280}

Change-Id: Ib257e30273f382d19ec922e2fa3279c39e918cde
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2859847
Auto-Submit: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#74282}
This commit is contained in:
Maya Lekova 2021-04-29 15:31:28 +00:00 committed by V8 LUCI CQ
parent 19b705682c
commit 14bc096e31
1 changed files with 11 additions and 28 deletions
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39
test/unittests/heap/cppgc/stack-unittest.cc
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@ -308,8 +308,6 @@ TEST_F(GCStackTest, IteratePointersFindsParameterNesting8) {
#ifdef FOR_ALL_CALLEE_SAVED_REGS
// Note: the test is brittle and can fail on some archs/configurations (see
// below).
TEST_F(GCStackTest, IteratePointersFindsCalleeSavedRegisters) {
auto scanner = std::make_unique<StackScanner>();
@ -329,32 +327,17 @@ TEST_F(GCStackTest, IteratePointersFindsCalleeSavedRegisters) {
// Moves |local_scanner->needle()| into a callee-saved register, leaving the
// callee-saved register as the only register referencing the needle.
// (Ignoring implementation-dependent dirty registers/stack.)
//
// Subtle: between the first inline assembly and the IteratePointers() call the
// compiler can clobber the tested register. Moving this tricky part into a
// noninlinable lambda allows to reduce pressure from the register allocator and
// thereby avoid such clobbering.
#define KEEP_ALIVE_FROM_CALLEE_SAVED(reg) \
{ \
local_scanner->Reset(); \
const bool found = [local_scanner, local_stack]() V8_NOINLINE { \
/* This moves the temporary into the callee-saved register. */ \
asm volatile("mov %0, %%" reg \
: \
: "r"(local_scanner->needle()) \
: "memory", reg); \
/* Register is unprotected from here till the actual invocation. The \
* compiler is free to clobber the register which makes the test \
* fail. */ \
local_stack->IteratePointers(local_scanner); \
/* Clear out the register again */ \
asm volatile("mov $0, %%" reg : : : "memory", reg); \
return local_scanner->found(); \
}(); \
EXPECT_TRUE(found) \
<< "pointer in callee-saved register not found. register: " << reg \
<< std::endl; \
}
#define KEEP_ALIVE_FROM_CALLEE_SAVED(reg) \
local_scanner->Reset(); \
/* This moves the temporary into the calee-saved register. */ \
asm("mov %0, %%" reg : : "r"(local_scanner->needle()) : reg); \
/* Register is unprotected from here till the actual invocation. */ \
local_stack->IteratePointers(local_scanner); \
EXPECT_TRUE(local_scanner->found()) \
<< "pointer in callee-saved register not found. register: " << reg \
<< std::endl; \
/* Clear out the register again */ \
asm("mov $0, %%" reg : : : reg);
FOR_ALL_CALLEE_SAVED_REGS(KEEP_ALIVE_FROM_CALLEE_SAVED)
#undef KEEP_ALIVE_FROM_CALLEE_SAVED