From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 27 Oct 2021 18:36:23 +0000 (-0700)
Subject: [LowerTypeTests] Emit cfi_jt aliases regardless of function export
X-Git-Tag: upstream/15.0.7~27452
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3ccd041af920125595a992becd0e1e4083ce562b;p=platform%2Fupstream%2Fllvm.git

[LowerTypeTests] Emit cfi_jt aliases regardless of function export

A constant complaint we get is that the __typeid__ symbols in the CFI
jump tables causes confusing stack traces in applications. Emit the more
readable cfi_jt aliases regardless of function export (LTO vs Thin LTO).

Reviewed By: pcc, tejohnson

Differential Revision: https://reviews.llvm.org/D107934
---

diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
index 340baff..26aa858 100644
--- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -1561,17 +1561,28 @@ void LowerTypeTestsModule::buildBitSetsFromFunctionsNative(
               ArrayRef<Constant *>{ConstantInt::get(IntPtrTy, 0),
                                    ConstantInt::get(IntPtrTy, I)}),
           F->getType());
-      if (Functions[I]->isExported()) {
-        if (IsJumpTableCanonical) {
-          ExportSummary->cfiFunctionDefs().insert(std::string(F->getName()));
-        } else {
-          GlobalAlias *JtAlias = GlobalAlias::create(
-              F->getValueType(), 0, GlobalValue::ExternalLinkage,
-              F->getName() + ".cfi_jt", CombinedGlobalElemPtr, &M);
+
+      const bool IsExported = Functions[I]->isExported();
+      if (!IsJumpTableCanonical) {
+        GlobalValue::LinkageTypes LT = IsExported
+                                           ? GlobalValue::ExternalLinkage
+                                           : GlobalValue::InternalLinkage;
+        GlobalAlias *JtAlias = GlobalAlias::create(F->getValueType(), 0, LT,
+                                                   F->getName() + ".cfi_jt",
+                                                   CombinedGlobalElemPtr, &M);
+        if (IsExported)
           JtAlias->setVisibility(GlobalValue::HiddenVisibility);
+        else
+          appendToUsed(M, {JtAlias});
+      }
+
+      if (IsExported) {
+        if (IsJumpTableCanonical)
+          ExportSummary->cfiFunctionDefs().insert(std::string(F->getName()));
+        else
           ExportSummary->cfiFunctionDecls().insert(std::string(F->getName()));
-        }
       }
+
       if (!IsJumpTableCanonical) {
         if (F->hasExternalWeakLinkage())
           replaceWeakDeclarationWithJumpTablePtr(F, CombinedGlobalElemPtr,
diff --git a/llvm/test/LTO/X86/cfi_jt_aliases.ll b/llvm/test/LTO/X86/cfi_jt_aliases.ll
new file mode 100644
index 0000000..d5d85d0
--- /dev/null
+++ b/llvm/test/LTO/X86/cfi_jt_aliases.ll
@@ -0,0 +1,112 @@
+; Full LTO test
+; RUN: opt %s -o %t.bc
+; RUN: llvm-lto2 run -o %t.o %t.bc -save-temps \
+; RUN:   -r=%t.bc,a,px \
+; RUN:   -r=%t.bc,b,px \
+; RUN:   -r=%t.bc,c,px \
+; RUN:   -r=%t.bc,d,px
+; RUN: llvm-readelf --symbols %t.o.0 | grep \.cfi_jt | FileCheck --check-prefix=CHECK-FULL-RE %s
+; RUN: llvm-objdump -dr %t.o.0 | FileCheck --check-prefix=CHECK-FULL-OD %s
+; RUN: llvm-dis %t.o.0.4.opt.bc -o - | FileCheck --check-prefix=CHECK-USED %s
+; Thin LTO test
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit %s -o %t.bc
+; RUN: llvm-lto2 run -o %t.o %t.bc \
+; RUN:   -r=%t.bc,a,px \
+; RUN:   -r=%t.bc,b,px \
+; RUN:   -r=%t.bc,c,px \
+; RUN:   -r=%t.bc,d,px
+; RUN: llvm-readelf --symbols %t.o.0 | grep \.cfi_jt | FileCheck --check-prefix=CHECK-THIN-RE %s
+; RUN: llvm-objdump -dr %t.o.0 | FileCheck --check-prefix=CHECK-THIN-OD %s
+
+; CHECK-FULL-RE:      FUNC LOCAL DEFAULT {{[0-9]+}} a.cfi_jt
+; CHECK-FULL-RE-NEXT: FUNC LOCAL DEFAULT {{[0-9]+}} b.cfi_jt
+; CHECK-FULL-RE-NEXT: FUNC LOCAL DEFAULT {{[0-9]+}} c.cfi_jt
+
+; CHECK-THIN-RE:      FUNC GLOBAL HIDDEN {{[0-9]+}} b.cfi_jt
+; CHECK-THIN-RE-NEXT: FUNC GLOBAL HIDDEN {{[0-9]+}} c.cfi_jt
+; CHECK-THIN-RE-NEXT: FUNC GLOBAL HIDDEN {{[0-9]+}} a.cfi_jt
+
+; CHECK-FULL-OD:      a.cfi_jt>:
+; CHECK-FULL-OD:      jmp {{.*}} <a.cfi_jt
+; CHECK-FULL-OD-NEXT: R_X86_64_PLT32 .La$local
+; CHECK-FULL-OD:      b.cfi_jt>:
+; CHECK-FULL-OD:      jmp {{.*}} <b.cfi_jt
+; CHECK-FULL-OD-NEXT: R_X86_64_PLT32 .Lb$local
+; CHECK-FULL-OD:      c.cfi_jt>:
+; CHECK-FULL-OD:      jmp {{.*}} <c.cfi_jt
+; CHECK-FULL-OD-NEXT: R_X86_64_PLT32 .Lc$local
+
+; CHECK-THIN-OD:      b.cfi_jt>:
+; CHECK-THIN-OD:      jmp {{.*}} <b.cfi_jt
+; CHECK-THIN-OD-NEXT: R_X86_64_PLT32 b
+; CHECK-THIN-OD:      c.cfi_jt>:
+; CHECK-THIN-OD:      jmp {{.*}} <c.cfi_jt
+; CHECK-THIN-OD-NEXT: R_X86_64_PLT32 c
+; CHECK-THIN-OD:      a.cfi_jt>:
+; CHECK-THIN-OD:      jmp {{.*}} <a.cfi_jt
+; CHECK-THIN-OD-NEXT: R_X86_64_PLT32 a
+
+; CHECK-USED: @llvm.used = appending global [3 x i8*] [i8* bitcast (void ()* @a.cfi_jt to i8*), i8* bitcast (void ()* @b.cfi_jt to i8*), i8* bitcast (void ()* @c.cfi_jt to i8*)], section "llvm.metadata"
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@f = internal global [4 x void ()*] [void ()* @a, void ()* @b, void ()* @c, void ()* null], align 16
+
+define dso_local void @a() !type !5 !type !6 { ret void }
+define dso_local void @b() !type !5 !type !6 { ret void }
+define dso_local void @c() !type !5 !type !6 { ret void }
+
+define dso_local void @d() !type !5 !type !6 {
+entry:
+  %i = alloca i32, align 4
+  store i32 0, i32* %i, align 4
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %0 = load i32, i32* %i, align 4
+  %idxprom = sext i32 %0 to i64
+  %arrayidx = getelementptr inbounds [4 x void ()*], [4 x void ()*]* @f, i64 0, i64 %idxprom
+  %1 = load void ()*, void ()** %arrayidx, align 8
+  %tobool = icmp ne void ()* %1, null
+  br i1 %tobool, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %2 = load i32, i32* %i, align 4
+  %idxprom1 = sext i32 %2 to i64
+  %arrayidx2 = getelementptr inbounds [4 x void ()*], [4 x void ()*]* @f, i64 0, i64 %idxprom1
+  %3 = load void ()*, void ()** %arrayidx2, align 8
+  %4 = bitcast void ()* %3 to i8*, !nosanitize !7
+  %5 = call i1 @llvm.type.test(i8* %4, metadata !"_ZTSFvvE"), !nosanitize !7
+  br i1 %5, label %cont, label %trap, !nosanitize !7
+
+trap:                                             ; preds = %for.body
+  call void @llvm.ubsantrap(i8 2), !nosanitize !7
+  unreachable, !nosanitize !7
+
+cont:                                             ; preds = %for.body
+  call void %3()
+  br label %for.inc
+
+for.inc:                                          ; preds = %cont
+  %6 = load i32, i32* %i, align 4
+  %inc = add nsw i32 %6, 1
+  store i32 %inc, i32* %i, align 4
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret void
+}
+
+declare i1 @llvm.type.test(i8*, metadata)
+declare void @llvm.ubsantrap(i8 immarg)
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 4, !"CFI Canonical Jump Tables", i32 0}
+!2 = !{i32 7, !"uwtable", i32 1}
+!3 = !{i32 7, !"frame-pointer", i32 2}
+!5 = !{i64 0, !"_ZTSFvvE"}
+!6 = !{i64 0, !"_ZTSFvvE.generalized"}
+!7 = !{}