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Reland "[ptr-compr] Switch to 31 bit Smis on 64-bit architectures"

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This is a reland of 12a9ee3a5b

Fixed arm64 disasm test.

Original change's description:
> [ptr-compr] Switch to 31 bit Smis on 64-bit architectures
>
> 32 bit Smis are incompatible with pointer compression so we land disable
> them before enabling pointer compression in order to separate memory and
> performance regressions caused by 31 bit Smis from pointer compression
> change.
>
> Bug: v8:9767
> Change-Id: I3d4a675df4208f808b1ba6e7816be545eae0dc24
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1815249
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63934}

Bug: v8:9767
Change-Id: Ife46a4240141dd89d841eac152032ad6ca471810
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1820939
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63940}
This commit is contained in:
Igor Sheludko 2019-09-24 11:19:57 +02:00 committed by Commit Bot
parent c199f828a8
commit d68bf369cb
3 changed files with 9 additions and 5 deletions
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2
BUILD.gn
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@ -108,7 +108,7 @@ declare_args() {
# Enable pointer compression (sets -dV8_COMPRESS_POINTERS).
v8_enable_pointer_compression = false
v8_enable_31bit_smis_on_64bit_arch = false
v8_enable_31bit_smis_on_64bit_arch = true
# Sets -dOBJECT_PRINT.
v8_enable_object_print = ""

2
src/codegen/code-stub-assembler.cc
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@ -1146,7 +1146,7 @@ TNode<BoolT> CodeStubAssembler::TaggedIsPositiveSmi(SloppyTNode<Object> a) {
return Word32Equal(
Word32And(
TruncateIntPtrToInt32(BitcastTaggedToWordForTagAndSmiBits(a)),
Uint32Constant(kSmiTagMask | static_cast<int32_t>(kSmiSignMask))),
Uint32Constant(static_cast<uint32_t>(kSmiTagMask | kSmiSignMask))),
Int32Constant(0));
#else
return WordEqual(WordAnd(BitcastTaggedToWordForTagAndSmiBits(a),

10
test/cctest/test-poison-disasm-arm64.cc
View File

@ -135,9 +135,13 @@ TEST(DisasmPoisonPolymorphicLoad) {
"b.ne", // deopt if different
"csel " + kPReg + ", xzr, " + kPReg + ", ne", // update the poison
"csdb", // spec. barrier
"ldur <<Field:x[0-9]+>>, \\[<<Obj>>, #[0-9]+\\]", // load the field
"and <<Field>>, <<Field>>, " + kPReg, // apply the poison
"asr x[0-9]+, <<Field>>, #32", // untag
"ldur x<<Field:[0-9]+>>, \\[<<Obj>>, #[0-9]+\\]", // load the field
"and x<<Field>>, x<<Field>>, " + kPReg, // apply the poison
#ifdef V8_31BIT_SMIS_ON_64BIT_ARCH
"asr w<<Field>>, w<<Field>>, #1", // untag
#else
"asr x[0-9]+, x<<Field>>, #32", // untag
#endif
"b", // goto merge point
// Lcase1:
"csel " + kPReg + ", xzr, " + kPReg + ", ne", // update the poison