File mozilla-bmo1375074.patch of Package MozillaFirefox.11699

# HG changeset patch
# User msirringhaus@suse.de
# Date 1519822672 -3600
#      Wed Feb 28 13:57:52 2018 +0100
# Node ID 8ba5f9a48bebbcd43f159035449544313ab056eb
# Parent  7e70a7a62a6b1b54aa4a520f1bcb6695c3a0214d
changeset:   407879:800abe66894d
user:        Lars T Hansen <lhansen@mozilla.com>
files:       js/src/jit-test/tests/bug1375074.js js/src/vm/UnboxedObject.cpp
description:
Bug 1375074 - Save and restore non-volatile x28 on ARM64 for generated unboxed object constructor.  r=sstangl

diff -r 7e70a7a62a6b -r 8ba5f9a48beb js/src/jit-test/tests/bug1375074.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/bug1375074.js	Wed Feb 28 13:57:52 2018 +0100
@@ -0,0 +1,18 @@
+// This forces the VM to start creating unboxed objects and thus stresses a
+// particular path into generated code for a specialized unboxed object
+// constructor.
+
+var K = 2000;			// 2000 should be plenty
+var s = "[";
+var i;
+for ( i=0; i < K-1; i++ )
+    s = s + `{"i":${i}},`;
+s += `{"i":${i}}]`;
+var v = JSON.parse(s);
+
+assertEq(v.length == K, true);
+
+for ( i=0; i < K; i++) {
+    assertEq(v[i] instanceof Object, true);
+    assertEq(v[i].i, i);
+}
diff -r 7e70a7a62a6b -r 8ba5f9a48beb js/src/vm/UnboxedObject.cpp
--- a/js/src/vm/UnboxedObject.cpp	Thu Mar 30 14:53:00 2017 -0400
+++ b/js/src/vm/UnboxedObject.cpp	Wed Feb 28 13:57:52 2018 +0100
@@ -86,8 +86,15 @@
 #endif
 
 #ifdef JS_CODEGEN_ARM64
-  // ARM64 communicates stack address via sp, but uses a pseudo-sp for
-  // addressing.
+  // ARM64 communicates stack address via sp, but uses a pseudo-sp (PSP) for
+  // addressing.  The register we use for PSP may however also be used by
+  // calling code, and it is nonvolatile, so save it.  Do this as a special
+  // case first because the generic save/restore code needs the PSP to be
+  // initialized already.
+  MOZ_ASSERT(PseudoStackPointer64.Is(masm.GetStackPointer64()));
+  masm.Str(PseudoStackPointer64, vixl::MemOperand(sp, -16, vixl::PreIndex));
+
+  // Initialize the PSP from the SP.
   masm.initStackPtr();
 #endif
 
@@ -239,7 +246,22 @@
   if (ScratchDoubleReg.volatile_()) masm.pop(ScratchDoubleReg);
   masm.PopRegsInMask(savedNonVolatileRegisters);
 
-  masm.abiret();
+#ifdef JS_CODEGEN_ARM64
+    // Now restore the value that was in the PSP register on entry, and return.
+
+    // Obtain the correct SP from the PSP.
+    masm.Mov(sp, PseudoStackPointer64);
+
+    // Restore the saved value of the PSP register, this value is whatever the
+    // caller had saved in it, not any actual SP value, and it must not be
+    // overwritten subsequently.
+    masm.Ldr(PseudoStackPointer64, vixl::MemOperand(sp, 16, vixl::PostIndex));
+
+    // Perform a plain Ret(), as abiret() will move SP <- PSP and that is wrong.
+    masm.Ret(vixl::lr);
+#else
+    masm.abiret();
+#endif
 
   masm.bind(&failureStoreOther);