ART: ARM64 art_quick_string_compareto
A simple implementation of the assembly stub for ARM64.
Make the string_compareto test in stub_test more interesting by
having strings with offsets in their backing arrays.
Change-Id: Ibc3a1bdb70e3764baa6b8e793987166c67b6fb39
diff --git a/runtime/arch/arm64/quick_entrypoints_arm64.S b/runtime/arch/arm64/quick_entrypoints_arm64.S
index 85a2c9e..7b66613 100644
--- a/runtime/arch/arm64/quick_entrypoints_arm64.S
+++ b/runtime/arch/arm64/quick_entrypoints_arm64.S
@@ -1435,4 +1435,118 @@
UNIMPLEMENTED art_quick_shr_long
UNIMPLEMENTED art_quick_ushr_long
UNIMPLEMENTED art_quick_indexof
-UNIMPLEMENTED art_quick_string_compareto
+
+ /*
+ * String's compareTo.
+ *
+ * TODO: Not very optimized.
+ *
+ * On entry:
+ * x0: this object pointer
+ * x1: comp object pointer
+ *
+ */
+ .extern __memcmp16
+ENTRY art_quick_string_compareto
+ mov x2, x0 // x0 is return, use x2 for first input.
+ sub x0, x2, x1 // Same string object?
+ cbnz x0,1f
+ ret
+1: // Different string objects.
+
+ ldr w6, [x2, #STRING_OFFSET_OFFSET]
+ ldr w5, [x1, #STRING_OFFSET_OFFSET]
+ ldr w4, [x2, #STRING_COUNT_OFFSET]
+ ldr w3, [x1, #STRING_COUNT_OFFSET]
+ ldr w2, [x2, #STRING_VALUE_OFFSET]
+ ldr w1, [x1, #STRING_VALUE_OFFSET]
+
+ /*
+ * Now: CharArray* Offset Count
+ * first arg x2 w6 w4
+ * second arg x1 w5 w3
+ */
+
+ // x0 := str1.length(w4) - str2.length(w3). ldr zero-extended w3/w4 into x3/x4.
+ subs x0, x4, x3
+ // Min(count1, count2) into w3.
+ csel x3, x3, x4, ge
+
+ // Build pointer into string data.
+
+ // Add offset in array (substr etc.) (sign extend and << 1).
+ add x2, x2, w6, sxtw #1
+ add x1, x1, w5, sxtw #1
+
+ // Add offset in CharArray to array.
+ add x2, x2, #STRING_DATA_OFFSET
+ add x1, x1, #STRING_DATA_OFFSET
+
+ // Check for long string, do memcmp16 for them.
+ cmp w3, #28 // Constant from arm32.
+ bgt .Ldo_memcmp16
+
+ /*
+ * Now:
+ * x2: *first string data
+ * x1: *second string data
+ * w3: iteration count
+ * x0: return value if comparison equal
+ * x4, x5, x6, x7: free
+ */
+
+ // Do a simple unrolled loop.
+.Lloop:
+ // At least two more elements?
+ subs w3, w3, #2
+ b.lt .Lremainder_or_done
+
+ ldrh w4, [x2], #2
+ ldrh w5, [x1], #2
+
+ ldrh w6, [x2], #2
+ ldrh w7, [x1], #2
+
+ subs w4, w4, w5
+ b.ne .Lw4_result
+
+ subs w6, w6, w7
+ b.ne .Lw6_result
+
+ b .Lloop
+
+.Lremainder_or_done:
+ adds w3, w3, #1
+ b.eq .Lremainder
+ ret
+
+.Lremainder:
+ ldrh w4, [x2], #2
+ ldrh w5, [x1], #2
+ subs w4, w4, w5
+ b.ne .Lw4_result
+ ret
+
+// Result is in w4
+.Lw4_result:
+ sxtw x0, w4
+ ret
+
+// Result is in w6
+.Lw6_result:
+ sxtw x0, w6
+ ret
+
+.Ldo_memcmp16:
+ str x0, [sp,#-16]! // Save x0
+
+ mov x0, x2
+ uxtw x2, w3
+ bl __memcmp16
+
+ ldr x1, [sp], #16 // Restore old x0 = length diff
+
+ cmp x0, #0 // Check the memcmp difference
+ csel x0, x0, x1, ne // x0 := x0 != 0 ? x0 : x1
+ ret
+END art_quick_string_compareto
diff --git a/runtime/arch/stub_test.cc b/runtime/arch/stub_test.cc
index 1a93767..94a7598 100644
--- a/runtime/arch/stub_test.cc
+++ b/runtime/arch/stub_test.cc
@@ -784,14 +784,14 @@
}
-#if defined(__i386__) || defined(__arm__) || defined(__x86_64__)
+#if defined(__i386__) || defined(__arm__) || defined(__aarch64__) || defined(__x86_64__)
extern "C" void art_quick_string_compareto(void);
#endif
TEST_F(StubTest, StringCompareTo) {
TEST_DISABLED_FOR_HEAP_REFERENCE_POISONING();
-#if defined(__i386__) || defined(__arm__) || defined(__x86_64__)
+#if defined(__i386__) || defined(__arm__) || defined(__aarch64__) || defined(__x86_64__)
// TODO: Check the "Unresolved" allocation stubs
Thread* self = Thread::Current();
