release/21.x: [AArch64][PAC][GISel] Add missing clobbering info to LOADgotAUTH (#157433) #160668
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…m#157433) When LOADgotAUTH is selected by GlobalISel, the existing MachineInstr is updated in-place instead of constructing a fresh instance by calling MIB.buildInstr(). This way, implicit-def operands have to be added manually for machine passes to take them into account. This patch fixes miscompilation possibility observed when compiling with GlobalISel enabled or at -O0 optimization level. (cherry picked from commit cff5a43)
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@aemerson What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-llvm-globalisel @llvm/pr-subscribers-backend-aarch64 Author: None (llvmbot) ChangesBackport cff5a43 Requested by: @atrosinenko Full diff: https://github.com/llvm/llvm-project/pull/160668.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp b/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
index 1381a9b70df87..450915518cc2f 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
@@ -2977,10 +2977,10 @@ bool AArch64InstructionSelector::select(MachineInstr &I) {
}
if (OpFlags & AArch64II::MO_GOT) {
- I.setDesc(TII.get(MF.getInfo<AArch64FunctionInfo>()->hasELFSignedGOT()
- ? AArch64::LOADgotAUTH
- : AArch64::LOADgot));
+ bool IsGOTSigned = MF.getInfo<AArch64FunctionInfo>()->hasELFSignedGOT();
+ I.setDesc(TII.get(IsGOTSigned ? AArch64::LOADgotAUTH : AArch64::LOADgot));
I.getOperand(1).setTargetFlags(OpFlags);
+ I.addImplicitDefUseOperands(MF);
} else if (TM.getCodeModel() == CodeModel::Large &&
!TM.isPositionIndependent()) {
// Materialize the global using movz/movk instructions.
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/ptrauth-elf-got.mir b/llvm/test/CodeGen/AArch64/GlobalISel/ptrauth-elf-got.mir
new file mode 100644
index 0000000000000..faf2cb8221ec7
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/ptrauth-elf-got.mir
@@ -0,0 +1,23 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
+# RUN: llc -O0 -mtriple=aarch64-linux-gnu -relocation-model=pic -run-pass=instruction-select -global-isel-abort=1 -verify-machineinstrs %s -o - | FileCheck %s
+
+--- |
+ @var_got = external global i8
+ define ptr @loadgotauth_implicit_defs() { ret ptr null }
+
+ !llvm.module.flags = !{!0}
+ !0 = !{i32 8, !"ptrauth-elf-got", i32 1}
+...
+
+---
+name: loadgotauth_implicit_defs
+legalized: true
+regBankSelected: true
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: loadgotauth_implicit_defs
+ ; CHECK: [[LOADgotAUTH:%[0-9]+]]:gpr64common = LOADgotAUTH target-flags(aarch64-got) @var_got, implicit-def $x16, implicit-def $x17, implicit-def $nzcv
+ ; CHECK-NEXT: $x0 = COPY [[LOADgotAUTH]]
+ %0:gpr(p0) = G_GLOBAL_VALUE @var_got
+ $x0 = COPY %0(p0)
+...
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Hi @aemerson, can you review this patch and approve it if you feel it should be merged into the release branch? |
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Backport cff5a43
Requested by: @atrosinenko