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Unified Diff: src/arm64/macro-assembler-arm64-inl.h

Issue 264773004: Arm64: Ensure that csp is always aligned to 16 byte values even if jssp is not. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Sync Created 6 years, 7 months ago
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Index: src/arm64/macro-assembler-arm64-inl.h
diff --git a/src/arm64/macro-assembler-arm64-inl.h b/src/arm64/macro-assembler-arm64-inl.h
index 7c9258a9ca363aa13c7bcf9f1bb4511a52aa137f..d97e60391fef794bf9b485b17b02cccb7cee10ef 100644
--- a/src/arm64/macro-assembler-arm64-inl.h
+++ b/src/arm64/macro-assembler-arm64-inl.h
@@ -1246,29 +1246,56 @@ void MacroAssembler::Uxtw(const Register& rd, const Register& rn) {
void MacroAssembler::BumpSystemStackPointer(const Operand& space) {
ASSERT(!csp.Is(sp_));
- // TODO(jbramley): Several callers rely on this not using scratch registers,
- // so we use the assembler directly here. However, this means that large
- // immediate values of 'space' cannot be handled cleanly. (Only 24-bits
- // immediates or values of 'space' that can be encoded in one instruction are
- // accepted.) Once we implement our flexible scratch register idea, we could
- // greatly simplify this function.
- InstructionAccurateScope scope(this);
- if ((space.IsImmediate()) && !is_uint12(space.immediate())) {
- // The subtract instruction supports a 12-bit immediate, shifted left by
- // zero or 12 bits. So, in two instructions, we can subtract any immediate
- // between zero and (1 << 24) - 1.
- int64_t imm = space.immediate();
- ASSERT(is_uint24(imm));
-
- int64_t imm_top_12_bits = imm >> 12;
- sub(csp, StackPointer(), imm_top_12_bits << 12);
- imm -= imm_top_12_bits << 12;
- if (imm > 0) {
- sub(csp, csp, imm);
+ { InstructionAccurateScope scope(this);
+ if (!TmpList()->IsEmpty()) {
+ if (CpuFeatures::IsSupported(ALWAYS_ALIGN_CSP)) {
+ UseScratchRegisterScope temps(this);
+ Register temp = temps.AcquireX();
+ sub(temp, StackPointer(), space);
+ bic(csp, temp, 0xf);
+ } else {
+ sub(csp, StackPointer(), space);
+ }
+ } else {
+ // TODO(jbramley): Several callers rely on this not using scratch
+ // registers, so we use the assembler directly here. However, this means
+ // that large immediate values of 'space' cannot be handled cleanly. (Only
+ // 24-bits immediates or values of 'space' that can be encoded in one
+ // instruction are accepted.) Once we implement our flexible scratch
+ // register idea, we could greatly simplify this function.
+ ASSERT(space.IsImmediate());
+ // Align to 16 bytes.
+ uint64_t imm = RoundUp(space.immediate(), 0x10);
+ ASSERT(is_uint24(imm));
+
+ Register source = StackPointer();
+ if (CpuFeatures::IsSupported(ALWAYS_ALIGN_CSP)) {
+ bic(csp, source, 0xf);
+ source = csp;
+ }
+ if (!is_uint12(imm)) {
+ int64_t imm_top_12_bits = imm >> 12;
+ sub(csp, source, imm_top_12_bits << 12);
+ source = csp;
+ imm -= imm_top_12_bits << 12;
+ }
+ if (imm > 0) {
+ sub(csp, source, imm);
+ }
}
- } else {
- sub(csp, StackPointer(), space);
}
+ AssertStackConsistency();
+}
+
+
+void MacroAssembler::SyncSystemStackPointer() {
+ ASSERT(emit_debug_code());
+ ASSERT(!csp.Is(sp_));
+ if (CpuFeatures::IsSupported(ALWAYS_ALIGN_CSP)) {
+ InstructionAccurateScope scope(this);
+ bic(csp, StackPointer(), 0xf);
+ }
+ AssertStackConsistency();
}
@@ -1540,7 +1567,7 @@ void MacroAssembler::Drop(uint64_t count, uint64_t unit_size) {
// It is safe to leave csp where it is when unwinding the JavaScript stack,
// but if we keep it matching StackPointer, the simulator can detect memory
// accesses in the now-free part of the stack.
- Mov(csp, StackPointer());
+ SyncSystemStackPointer();
}
}
@@ -1562,7 +1589,7 @@ void MacroAssembler::Drop(const Register& count, uint64_t unit_size) {
// It is safe to leave csp where it is when unwinding the JavaScript stack,
// but if we keep it matching StackPointer, the simulator can detect memory
// accesses in the now-free part of the stack.
- Mov(csp, StackPointer());
+ SyncSystemStackPointer();
}
}
@@ -1584,7 +1611,7 @@ void MacroAssembler::DropBySMI(const Register& count_smi, uint64_t unit_size) {
// It is safe to leave csp where it is when unwinding the JavaScript stack,
// but if we keep it matching StackPointer, the simulator can detect memory
// accesses in the now-free part of the stack.
- Mov(csp, StackPointer());
+ SyncSystemStackPointer();
}
}
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