[llvm] 5422e2c - [AArch64][GlobalISel] On Darwin don't fold globals into the offset of prefetches.

[Amara Emerson via llvm-commits]

Author: Amara Emerson
Date: 2025-03-05T16:06:08-08:00
New Revision: 5422e2c68107650c33f39e6224d1ff0064467550

URL: https://github.com/llvm/llvm-project/commit/5422e2c68107650c33f39e6224d1ff0064467550
DIFF: https://github.com/llvm/llvm-project/commit/5422e2c68107650c33f39e6224d1ff0064467550.diff

LOG: [AArch64][GlobalISel] On Darwin don't fold globals into the offset of prefetches.

ld64 doesn't currently support the PAGEOFF relocations on anything but load/stores
so we need to bail-out here to fix the build failures on greendragon.

rdar://145495288

Added: 
    llvm/test/CodeGen/AArch64/GlobalISel/prefetch-darwin-no-fold-global.ll

Modified: 
    llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp b/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
index 1cc7480e44eae..67a08e39fe879 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
@@ -7617,7 +7617,12 @@ AArch64InstructionSelector::selectAddrModeIndexed(MachineOperand &Root,
 
   CodeModel::Model CM = MF.getTarget().getCodeModel();
   // Check if we can fold in the ADD of small code model ADRP + ADD address.
-  if (CM == CodeModel::Small) {
+  // HACK: ld64 on Darwin doesn't support relocations on PRFM, so we can't fold
+  // globals into the offset.
+  MachineInstr *RootParent = Root.getParent();
+  if (CM == CodeModel::Small &&
+      !(RootParent->getOpcode() == AArch64::G_AARCH64_PREFETCH &&
+        STI.isTargetDarwin())) {
     auto OpFns = tryFoldAddLowIntoImm(*RootDef, Size, MRI);
     if (OpFns)
       return OpFns;

diff  --git a/llvm/test/CodeGen/AArch64/GlobalISel/prefetch-darwin-no-fold-global.ll b/llvm/test/CodeGen/AArch64/GlobalISel/prefetch-darwin-no-fold-global.ll
new file mode 100644
index 0000000000000..f38d0ff2a64d6
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/prefetch-darwin-no-fold-global.ll
@@ -0,0 +1,30 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -global-isel -o - %s | FileCheck %s
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32"
+target triple = "arm64-apple-macosx14.0.0"
+
+%struct.S = type { ptr }
+
+ at str = global %struct.S zeroinitializer, align 8
+
+; Checks that on Darwin we don't fold the global into the prfm instruction
+; since ld64 doesn't support it.
+
+define void @test() #0 {
+; CHECK-LABEL: test:
+; CHECK:       ; %bb.0: ; %entry
+; CHECK-NEXT:  Lloh0:
+; CHECK-NEXT:    adrp x8, _str at PAGE
+; CHECK-NEXT:  Lloh1:
+; CHECK-NEXT:    add x8, x8, _str at PAGEOFF
+; CHECK-NEXT:    prfm pldl1strm, [x8]
+; CHECK-NEXT:    ret
+; CHECK-NEXT:    .loh AdrpAdd Lloh0, Lloh1
+entry:
+  call void @llvm.prefetch.p0(ptr @str, i32 0, i32 0, i32 1)
+  ret void
+}
+
+; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite, inaccessiblemem: readwrite)
+declare void @llvm.prefetch.p0(ptr nocapture readonly, i32 immarg, i32 immarg, i32 immarg) #1
+