Merge V8 5.3.332.45. DO NOT MERGE
Test: Manual
FPIIM-449
Change-Id: Id3254828b068abdea3cb10442e0172a8c9a98e03
(cherry picked from commit 13e2dadd00298019ed862f2b2fc5068bba730bcf)
diff --git a/src/s390/macro-assembler-s390.h b/src/s390/macro-assembler-s390.h
index 19f0f7c..23b353e 100644
--- a/src/s390/macro-assembler-s390.h
+++ b/src/s390/macro-assembler-s390.h
@@ -1582,17 +1582,29 @@
}
void IndexToArrayOffset(Register dst, Register src, int elementSizeLog2,
- bool isSmi) {
+ bool isSmi, bool keyMaybeNegative) {
if (isSmi) {
SmiToArrayOffset(dst, src, elementSizeLog2);
- } else {
+ } else if (keyMaybeNegative ||
+ !CpuFeatures::IsSupported(GENERAL_INSTR_EXT)) {
#if V8_TARGET_ARCH_S390X
+ // If array access is dehoisted, the key, being an int32, can contain
+ // a negative value, as needs to be sign-extended to 64-bit for
+ // memory access.
+ //
// src (key) is a 32-bit integer. Sign extension ensures
// upper 32-bit does not contain garbage before being used to
// reference memory.
lgfr(src, src);
#endif
ShiftLeftP(dst, src, Operand(elementSizeLog2));
+ } else {
+ // Small optimization to reduce pathlength. After Bounds Check,
+ // the key is guaranteed to be non-negative. Leverage RISBG,
+ // which also performs zero-extension.
+ risbg(dst, src, Operand(32 - elementSizeLog2),
+ Operand(63 - elementSizeLog2), Operand(elementSizeLog2),
+ true);
}
}