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[Memory] Treat AllocRange high_page_number as exclusive

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The free-block tracker search in BaseHeap::AllocRange treats
high_page_number as inclusive, shifting allocator-returned addresses
by one stride relative to the old loop-based search. Some titles
encode allocator-returned addresses in PPC code and break when that
layout shifts (Far Cry 3, Far Cry 4, Watchdogs).

In addition, reapply xe::align on the high side of AllocRange
(essentially reverting c28019e33). Without the round-up, a caller
passing a min/max window exactly the size of its request loses a
stride at the top and fails the early page_count size check.
This commit is contained in:
Herman S.
2026-04-14 13:59:45 +09:00
parent 763b160c7a
commit 4fcb8e4498
3 changed files with 33 additions and 19 deletions
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17
src/xenia/base/testing/heap_test.cc
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@@ -85,14 +85,15 @@ TEST_CASE("heap_alloc_basic", "[heap]") {
TEST_CASE("heap_alloc_top_down", "[heap]") {
TestHeap h(0x80000000, 0x100000, 0x1000);
// Top-down treats high_page_number as exclusive, so the top page is
// never handed out.
uint32_t addr = 0;
REQUIRE(h.Alloc(0x1000, 0x1000, true, &addr));
// Top-down: should be at the highest aligned address.
REQUIRE(addr == 0x800FF000);
REQUIRE(addr == 0x800FE000);
REQUIRE(h.unreserved_page_count() == 255);
REQUIRE(h.Alloc(0x2000, 0x1000, true, &addr));
REQUIRE(addr == 0x800FD000);
REQUIRE(addr == 0x800FC000);
REQUIRE(h.unreserved_page_count() == 253);
}
@@ -237,16 +238,18 @@ TEST_CASE("heap_alloc_alignment_top_down", "[heap]") {
// 1MB heap, 4KB pages
TestHeap h(0x80000000, 0x100000, 0x1000);
// Allocate 1 page at the top.
// Top-down skips the top page (0x800FF000), so a 1-page allocation
// lands on page 0xFE.
uint32_t first = 0;
REQUIRE(h.Alloc(0x1000, 0x1000, true, &first));
REQUIRE(first == 0x800FF000);
REQUIRE(first == 0x800FE000);
// Allocate with 64KB alignment top-down — should align down.
// 64KB-aligned top-down: stride 16, exclusive high at page 0xFF, so
// the highest aligned base is page 0xE0.
uint32_t aligned = 0;
REQUIRE(h.Alloc(0x1000, 0x10000, true, &aligned));
REQUIRE((aligned % 0x10000) == 0);
REQUIRE(aligned == 0x800F0000);
REQUIRE(aligned == 0x800E0000);
}
// ============================================================================