release/18.x: [llvm][AArch64] Autoupgrade function attributes from Module attributes. (#82763) #84039
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@nickdesaulniers What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-llvm-ir @llvm/pr-subscribers-lto Author: None (llvmbot) ChangesBackport ded5de1 Requested by: @DanielKristofKiss Full diff: https://github.com/llvm/llvm-project/pull/84039.diff 6 Files Affected:
diff --git a/llvm/include/llvm/IR/AutoUpgrade.h b/llvm/include/llvm/IR/AutoUpgrade.h
index 152f781ffa9b30..1ef32bcb121bec 100644
--- a/llvm/include/llvm/IR/AutoUpgrade.h
+++ b/llvm/include/llvm/IR/AutoUpgrade.h
@@ -88,6 +88,9 @@ namespace llvm {
/// info. Return true if module is modified.
bool UpgradeDebugInfo(Module &M);
+ /// Copies module attributes to the functions in the module.
+ void CopyModuleAttrToFunctions(Module &M);
+
/// Check whether a string looks like an old loop attachment tag.
inline bool mayBeOldLoopAttachmentTag(StringRef Name) {
return Name.starts_with("llvm.vectorizer.");
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
index b90bbe71ac1896..3b784b06397445 100644
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -5169,6 +5169,72 @@ void llvm::UpgradeFunctionAttributes(Function &F) {
Arg.removeAttrs(AttributeFuncs::typeIncompatible(Arg.getType()));
}
+// Check if the module attribute is present and not zero.
+static bool isModuleAttributeSet(Module &M, const StringRef &ModAttr) {
+ const auto *Attr =
+ mdconst::extract_or_null<ConstantInt>(M.getModuleFlag(ModAttr));
+ return Attr && Attr->getZExtValue();
+}
+
+// Copy an attribute from module to the function if exists.
+// First value of the pair is used when the module attribute is not zero
+// the second otherwise.
+static void
+CopyModuleAttributeToFunction(Function &F, StringRef FnAttrName,
+ StringRef ModAttrName,
+ std::pair<StringRef, StringRef> Values) {
+ if (F.hasFnAttribute(FnAttrName))
+ return;
+ F.addFnAttr(FnAttrName, isModuleAttributeSet(*F.getParent(), ModAttrName)
+ ? Values.first
+ : Values.second);
+}
+
+// Copy a boolean attribute from module to the function if exists.
+// Module attribute treated false if zero otherwise true.
+static void CopyModuleAttributeToFunction(Function &F, StringRef AttrName) {
+ CopyModuleAttributeToFunction(
+ F, AttrName, AttrName,
+ std::make_pair<StringRef, StringRef>("true", "false"));
+}
+
+// Copy an attribute from module to the function if exists.
+// First value of the pair is used when the module attribute is not zero
+// the second otherwise.
+static void
+CopyModuleAttributeToFunction(Function &F, StringRef AttrName,
+ std::pair<StringRef, StringRef> Values) {
+ CopyModuleAttributeToFunction(F, AttrName, AttrName, Values);
+}
+
+void llvm::CopyModuleAttrToFunctions(Module &M) {
+ Triple T(M.getTargetTriple());
+ if (!T.isThumb() && !T.isARM() && !T.isAArch64())
+ return;
+
+ for (Function &F : M.getFunctionList()) {
+ if (F.isDeclaration())
+ continue;
+
+ if (!F.hasFnAttribute("sign-return-address")) {
+ StringRef SignType = "none";
+ if (isModuleAttributeSet(M, "sign-return-address"))
+ SignType = "non-leaf";
+
+ if (isModuleAttributeSet(M, "sign-return-address-all"))
+ SignType = "all";
+
+ F.addFnAttr("sign-return-address", SignType);
+ }
+ CopyModuleAttributeToFunction(F, "branch-target-enforcement");
+ CopyModuleAttributeToFunction(F, "branch-protection-pauth-lr");
+ CopyModuleAttributeToFunction(F, "guarded-control-stack");
+ CopyModuleAttributeToFunction(
+ F, "sign-return-address-key",
+ std::make_pair<StringRef, StringRef>("b_key", "a_key"));
+ }
+}
+
static bool isOldLoopArgument(Metadata *MD) {
auto *T = dyn_cast_or_null<MDTuple>(MD);
if (!T)
diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
index 1bd562d1e8ae2b..40bdaf318d585b 100644
--- a/llvm/lib/Linker/IRMover.cpp
+++ b/llvm/lib/Linker/IRMover.cpp
@@ -1605,6 +1605,11 @@ Error IRLinker::run() {
// Loop over all of the linked values to compute type mappings.
computeTypeMapping();
+ // Convert module level attributes to function level attributes because
+ // after merging modules the attributes might change and would have different
+ // effect on the functions as the original module would have.
+ CopyModuleAttrToFunctions(*SrcM);
+
std::reverse(Worklist.begin(), Worklist.end());
while (!Worklist.empty()) {
GlobalValue *GV = Worklist.back();
diff --git a/llvm/test/LTO/AArch64/link-branch-target-enforcement.ll b/llvm/test/LTO/AArch64/link-branch-target-enforcement.ll
index ccf8cf67ede6dc..74d9c86881d52c 100644
--- a/llvm/test/LTO/AArch64/link-branch-target-enforcement.ll
+++ b/llvm/test/LTO/AArch64/link-branch-target-enforcement.ll
@@ -32,6 +32,7 @@ entry:
; CHECK-DUMP: <main>:
; CHECK-DUMP: bl 0x8 <main+0x8>
; CHECK-DUMP: <foo>:
+; CHECK-DUMP: paciasp
; `main` doesn't support BTI while `foo` does, so in the binary
; we should see only PAC which is supported by both.
diff --git a/llvm/test/LTO/AArch64/link-sign-return-address.ll b/llvm/test/LTO/AArch64/link-sign-return-address.ll
new file mode 100644
index 00000000000000..c25857ceed7b40
--- /dev/null
+++ b/llvm/test/LTO/AArch64/link-sign-return-address.ll
@@ -0,0 +1,43 @@
+; Testcase to check that module with different branch-target-enforcement can
+; be mixed.
+;
+; RUN: llvm-as %s -o %t1.bc
+; RUN: llvm-as %p/Inputs/foo.ll -o %t2.bc
+; RUN: llvm-lto -exported-symbol main \
+; RUN: -exported-symbol foo \
+; RUN: -filetype=obj \
+; RUN: %t2.bc %t1.bc \
+; RUN: -o %t1.exe 2>&1
+; RUN: llvm-objdump -d %t1.exe | FileCheck --check-prefix=CHECK-DUMP %s
+; RUN: llvm-readelf -n %t1.exe | FileCheck --allow-empty --check-prefix=CHECK-PROP %s
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-gnu"
+
+declare i32 @foo();
+
+define i32 @main() {
+entry:
+ %add = call i32 @foo()
+ ret i32 %add
+}
+
+!llvm.module.flags = !{!0, !1, !2, !3 }
+!0 = !{i32 8, !"branch-target-enforcement", i32 0}
+!1 = !{i32 8, !"sign-return-address", i32 0}
+!2 = !{i32 8, !"sign-return-address-all", i32 0}
+!3 = !{i32 8, !"sign-return-address-with-bkey", i32 0}
+
+; CHECK-DUMP: <foo>:
+; CHECK-DUMP: paciasp
+; CHECK-DUMP: mov w0, #0x2a
+; CHECK-DUMP: autiasp
+; CHECK-DUMP: ret
+; CHECK-DUMP: <main>:
+; CHECK-DUMP-NOT: paciasp
+; CHECK-DUMP: str x30,
+; CHECK-DUMP: bl 0x14 <main+0x4>
+
+; `main` doesn't support PAC sign-return-address while `foo` does, so in the binary
+; we should not see anything.
+; CHECK-PROP-NOT: Properties: aarch64 feature: PAC
\ No newline at end of file
diff --git a/llvm/test/Linker/link-arm-and-thumb.ll b/llvm/test/Linker/link-arm-and-thumb.ll
index a90f2128e4430a..37bd8c37f8b5e5 100644
--- a/llvm/test/Linker/link-arm-and-thumb.ll
+++ b/llvm/test/Linker/link-arm-and-thumb.ll
@@ -13,11 +13,12 @@ entry:
ret i32 %add
}
-; CHECK: define i32 @main() {
+; CHECK: define i32 @main() [[MAIN_ATTRS:#[0-9]+]]
; CHECK: define i32 @foo(i32 %a, i32 %b) [[ARM_ATTRS:#[0-9]+]]
; CHECK: define i32 @bar(i32 %a, i32 %b) [[THUMB_ATTRS:#[0-9]+]]
-; CHECK: attributes [[ARM_ATTRS]] = { "target-features"="-thumb-mode" }
-; CHECK: attributes [[THUMB_ATTRS]] = { "target-features"="+thumb-mode" }
+; CHECK: attributes [[MAIN_ATTRS]] = { {{.*}} }
+; CHECK: attributes [[ARM_ATTRS]] = { {{.*}} "target-features"="-thumb-mode" }
+; CHECK: attributes [[THUMB_ATTRS]] = { {{.*}} "target-features"="+thumb-mode" }
; STDERR-NOT: warning: Linking two modules of different target triples:
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…s. (llvm#82763) sign-return-address and similar module attributes should be propagated to the function level before got merged because module flags may contradict and this information is not recoverable. Generated code will match with the normal linking flow. Refactored version of (llvm#80640). Run the attribute copy only during IRMove. (cherry picked from commit ded5de1)
nickdesaulniers
approved these changes
Mar 5, 2024
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Note that a potential regression for this patch was reported at #82763 (comment). |
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Changing my mind here, we've identified the issue with this commit. |
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@nickdesaulniers So we should not backport this? |
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We'll have a 3rd iteration of the patch to backport. This version should not be. |
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Backport ded5de1
Requested by: @DanielKristofKiss