[JITLink][AArch32] Fix Unaligned Data Symbol Address Resolution (#97030)

The ARM architecture uses the LSB bit for ARM/Thumb mode switch
flagging. This is true for alignments of 2 and 4 but in data
relocations the alignment is 1 allowing the LSB bit to be set.
Now only `ELF::STT_FUNC` typed symbols are used in the 
TargetFlag mechanism.

The test is a minimal example of the issue mentioned below.

Fixes #95911 "Orc global constructor order test fails on 32
bit ARM".

Author: eymay

llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp

@@ -200,6 +200,9 @@ class ELFLinkGraphBuilder_aarch32
 
 protected:
   TargetFlagsType makeTargetFlags(const typename ELFT::Sym &Sym) override {
+    // Only emit target flag for callable symbols
+    if (Sym.getType() != ELF::STT_FUNC)
+      return TargetFlagsType{};
     if (Sym.getValue() & 0x01)
       return aarch32::ThumbSymbol;
     return TargetFlagsType{};
@@ -209,7 +212,9 @@ class ELFLinkGraphBuilder_aarch32
                                      TargetFlagsType Flags) override {
     assert((makeTargetFlags(Sym) & Flags) == Flags);
     static constexpr uint64_t ThumbBit = 0x01;
-    return Sym.getValue() & ~ThumbBit;
+    if (Sym.getType() == ELF::STT_FUNC)
+      return Sym.getValue() & ~ThumbBit;
+    return Sym.getValue();
   }
 
 public:

llvm/test/ExecutionEngine/JITLink/AArch32/ELF_data_alignment.s

@@ -0,0 +1,67 @@
+# RUN: llvm-mc -triple=armv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_armv7.o %s
+# RUN: llvm-objdump -s --section=.rodata %t_armv7.o | FileCheck --check-prefix=CHECK-OBJ %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN:              -slab-page-size 4096 %t_armv7.o -debug-only=jitlink 2>&1 \
+# RUN:              | FileCheck --check-prefix=CHECK-LG %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN:              -slab-page-size 4096 %t_armv7.o -check %s
+
+# RUN: llvm-mc -triple=thumbv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_thumbv7.o %s
+# RUN: llvm-objdump -s --section=.rodata %t_thumbv7.o | FileCheck --check-prefix=CHECK-OBJ %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN:              -slab-page-size 4096 %t_thumbv7.o -debug-only=jitlink 2>&1 \
+# RUN:              | FileCheck --check-prefix=CHECK-LG %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN:              -slab-page-size 4096 %t_thumbv7.o -check %s
+
+# The strings of "H1\00", "H2\00" and "H3\00" are encoded as
+#               0x483100, 0x483200 and 0x483300 in the .rodata section.
+# CHECK-OBJ: Contents of section .rodata:
+# CHECK-OBJ: 0000 48310048 32004833 00                 H1.H2.H3.
+
+# CHECK-LG: Starting link phase 1 for graph
+# CHECK-LG: section .rodata:
+
+# CHECK-LG:       block 0x0 size = 0x00000009, align = 1, alignment-offset = 0
+# CHECK-LG-NEXT:    symbols:
+# CHECK-LG-NEXT:      0x0 (block + 0x00000000): size: 0x00000003, linkage: strong, scope: default, live  -   Lstr.H1
+# CHECK-LG-NEXT:      0x3 (block + 0x00000003): size: 0x00000003, linkage: strong, scope: default, live  -   Lstr.H2
+# CHECK-LG-NOT:       0x2 (block + 0x00000002): size: 0x00000003, linkage: strong, scope: default, live  -   Lstr.H2
+# CHECK-LG-NEXT:      0x6 (block + 0x00000006): size: 0x00000003, linkage: strong, scope: default, live  -   Lstr.H3
+
+# jitlink-check: Lstr.H1 = 0x76ff0000
+# jitlink-check: (*{4}(Lstr.H1))[23:0] = 0x003148
+	.globl	Lstr.H1
+	.type	Lstr.H1,%object
+	.section	.rodata,"a",%progbits
+Lstr.H1:
+	.asciz	"H1"
+	.size	Lstr.H1, 3
+
+# H2 is unaligned as its beginning address is base address + 0x3
+# Make sure the string we get is 0x003248 and not 0x324800
+# jitlink-check: Lstr.H2 = 0x76ff0003
+# jitlink-check: (*{4}(Lstr.H2))[23:0] = 0x003248
+	.globl	Lstr.H2
+	.type	Lstr.H2,%object
+Lstr.H2:
+	.asciz	"H2"
+	.size	Lstr.H2, 3
+
+# jitlink-check: Lstr.H3 = 0x76ff0006
+# jitlink-check: (*{4}(Lstr.H3))[23:0] = 0x003348
+	.globl	Lstr.H3
+	.type	Lstr.H3,%object
+Lstr.H3:
+	.asciz	"H3"
+	.size	Lstr.H3, 3
+
+	.text
+	.syntax unified
+# Empty main function for jitlink to be happy
+	.globl	main
+	.type	main,%function
+	.p2align	2
+main:
+	bx	lr
+	.size	main,.-main

llvm/test/ExecutionEngine/Orc/global-ctor-order.ll

@@ -1,9 +1,5 @@
 ; Test that global constructors are correctly ordered
 ;
-; Uncovers a pre-existing issue on Arm 32 bit, see
-; https://github.com/llvm/llvm-project/issues/95911.
-; UNSUPPORTED: target=arm{{.*}}
-;
 ; RUN: lli -jit-kind=orc %s | FileCheck %s
 ;
 ; CHECK: H1