[JITLink][RISCV] Implement eh_frame handling (#68253)

This requires adding a `NegDelta32` edge kind that cannot be mapped to existing relocations. Co-authored-by: Job Noorman <jnoorman@igalia.com>
llvm · Oct 28, 2023 · 4f6757c · 4f6757c
1 parent fc6bdb8
commit 4f6757c
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Showing 7 changed files with 204 additions and 7 deletions.
diff --git a/clang/test/Interpreter/simple-exception.cpp b/clang/test/Interpreter/simple-exception.cpp
@@ -1,7 +1,7 @@
 // clang-format off
 // UNSUPPORTED: system-aix
-// XFAIL for arm, arm64, riscv, or running on Windows.
-// XFAIL: target={{(arm|riscv).*}}, system-windows
+// XFAIL for arm and arm64, or running on Windows.
+// XFAIL: target=arm{{.*}}, system-windows
 // RUN: cat %s | clang-repl | FileCheck %s
 
 // Incompatible with msan. It passes with -O3 but fail -Oz. Interpreter

diff --git a/clang/unittests/Interpreter/ExceptionTests/InterpreterExceptionTest.cpp b/clang/unittests/Interpreter/ExceptionTests/InterpreterExceptionTest.cpp
@@ -122,11 +122,6 @@ extern "C" int throw_exception() {
                               Triple.getArch() == llvm::Triple::aarch64_32))
     GTEST_SKIP();
 
-  // FIXME: RISC-V fails as .eh_frame handling is not yet implemented in
-  // JITLink for RISC-V. See PR #66067.
-  if (Triple.isRISCV())
-    GTEST_SKIP();
-
   llvm::cantFail(Interp->ParseAndExecute(ExceptionCode));
   testing::internal::CaptureStdout();
   auto ThrowException =

diff --git a/llvm/include/llvm/ExecutionEngine/JITLink/riscv.h b/llvm/include/llvm/ExecutionEngine/JITLink/riscv.h
@@ -214,6 +214,12 @@ enum EdgeKind_riscv : Edge::Kind {
   /// Linker relaxation will use this to ensure all code sequences are properly
   /// aligned and then remove these edges from the graph.
   AlignRelaxable,
+
+  /// 32-bit negative delta.
+  ///
+  /// Fixup expression:
+  ///   Fixup <- Fixup - Target + Addend
+  NegDelta32,
 };
 
 /// Returns a string name for the given riscv edge. For debugging purposes

diff --git a/llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp
@@ -11,10 +11,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/JITLink/ELF_riscv.h"
+#include "EHFrameSupportImpl.h"
 #include "ELFLinkGraphBuilder.h"
 #include "JITLinkGeneric.h"
 #include "PerGraphGOTAndPLTStubsBuilder.h"
 #include "llvm/BinaryFormat/ELF.h"
+#include "llvm/ExecutionEngine/JITLink/DWARFRecordSectionSplitter.h"
 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
 #include "llvm/ExecutionEngine/JITLink/riscv.h"
 #include "llvm/Object/ELF.h"
@@ -456,6 +458,13 @@ class ELFJITLinker_riscv : public JITLinker<ELFJITLinker_riscv> {
     case AlignRelaxable:
       // Ignore when the relaxation pass did not run
       break;
+    case NegDelta32: {
+      int64_t Value = FixupAddress - E.getTarget().getAddress() + E.getAddend();
+      if (LLVM_UNLIKELY(!isInRangeForImm(Value, 32)))
+        return makeTargetOutOfRangeError(G, B, E);
+      *(little32_t *)FixupPtr = static_cast<uint32_t>(Value);
+      break;
+    }
     }
     return Error::success();
   }
@@ -958,6 +967,13 @@ void link_ELF_riscv(std::unique_ptr<LinkGraph> G,
   PassConfiguration Config;
   const Triple &TT = G->getTargetTriple();
   if (Ctx->shouldAddDefaultTargetPasses(TT)) {
+
+    Config.PrePrunePasses.push_back(DWARFRecordSectionSplitter(".eh_frame"));
+    Config.PrePrunePasses.push_back(EHFrameEdgeFixer(
+        ".eh_frame", G->getPointerSize(), Edge::Invalid, Edge::Invalid,
+        Edge::Invalid, Edge::Invalid, NegDelta32));
+    Config.PrePrunePasses.push_back(EHFrameNullTerminator(".eh_frame"));
+
     if (auto MarkLive = Ctx->getMarkLivePass(TT))
       Config.PrePrunePasses.push_back(std::move(MarkLive));
     else

diff --git a/llvm/lib/ExecutionEngine/JITLink/riscv.cpp b/llvm/lib/ExecutionEngine/JITLink/riscv.cpp
@@ -82,6 +82,8 @@ const char *getEdgeKindName(Edge::Kind K) {
     return "CallRelaxable";
   case AlignRelaxable:
     return "AlignRelaxable";
+  case NegDelta32:
+    return "NegDelta32";
   }
   return getGenericEdgeKindName(K);
 }

diff --git a/llvm/test/ExecutionEngine/JITLink/RISCV/ELF_ehframe.s b/llvm/test/ExecutionEngine/JITLink/RISCV/ELF_ehframe.s
@@ -0,0 +1,74 @@
+# REQUIRES: asserts
+
+# RUN: llvm-mc -triple=riscv32-linux-gnu -mattr=+relax -filetype=obj -o %t.32.o %s
+# RUN: llvm-jitlink -noexec -phony-externals -debug-only=jitlink %t.32.o 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: llvm-mc -triple=riscv64-linux-gnu -mattr=+relax -filetype=obj -o %t.64.o %s
+# RUN: llvm-jitlink -noexec -phony-externals -debug-only=jitlink %t.64.o 2>&1 | \
+# RUN:   FileCheck %s
+
+# Check that splitting of eh-frame sections works.
+#
+# CHECK: DWARFRecordSectionSplitter: Processing .eh_frame...
+# CHECK:  Processing block at
+# CHECK:    Processing CFI record at
+# CHECK:      Extracted {{.*}} section = .eh_frame
+# CHECK:    Processing CFI record at
+# CHECK:      Extracted {{.*}} section = .eh_frame
+# CHECK: EHFrameEdgeFixer: Processing .eh_frame in "{{.*}}"...
+# CHECK:   Processing block at
+# CHECK:     Record is CIE
+# CHECK:   Processing block at
+# CHECK:     Record is FDE
+# CHECK:       Adding edge at {{.*}} to CIE at: {{.*}}
+# CHECK:       Existing edge at {{.*}} to PC begin at {{.*}}
+# CHECK:       Adding keep-alive edge from target at {{.*}} to FDE at {{.*}}
+# CHECK:   Processing block at
+# CHECK:     Record is FDE
+# CHECK:       Adding edge at {{.*}} to CIE at: {{.*}}
+# CHECK:       Existing edge at {{.*}} to PC begin at {{.*}}
+# CHECK:       Adding keep-alive edge from target at {{.*}} to FDE at {{.*}}
+
+## This is "int main { throw 1; }" compiled for riscv32. We use the 32-bit
+## version because it is also legal for riscv64.
+	.text
+	.globl	main
+	.p2align	1
+	.type	main,@function
+main:
+	.cfi_startproc
+	addi	sp, sp, -16
+	.cfi_def_cfa_offset 16
+	sw	ra, 12(sp)
+	.cfi_offset ra, -4
+	li	a0, 4
+	call	__cxa_allocate_exception
+	li	a1, 1
+	sw	a1, 0(a0)
+	lga a1, _ZTIi
+	li	a2, 0
+	call	__cxa_throw
+.Lfunc_end0:
+	.size	main, .Lfunc_end0-main
+	.cfi_endproc
+
+	.globl	dup
+	.p2align	1
+	.type	dup,@function
+dup:
+	.cfi_startproc
+	addi	sp, sp, -16
+	.cfi_def_cfa_offset 16
+	sw	ra, 12(sp)
+	.cfi_offset ra, -4
+	li	a0, 4
+	call	__cxa_allocate_exception
+	li	a1, 1
+	sw	a1, 0(a0)
+	lga a1, _ZTIi
+	li	a2, 0
+	call	__cxa_throw
+.Lfunc_end1:
+	.size	dup, .Lfunc_end1-dup
+	.cfi_endproc
diff --git a/llvm/test/ExecutionEngine/JITLink/RISCV/ELF_ehframe.test b/llvm/test/ExecutionEngine/JITLink/RISCV/ELF_ehframe.test
@@ -0,0 +1,104 @@
+# RUN: yaml2obj -DELFCLASS=ELFCLASS32 -o %t.32.o %s
+# RUN: llvm-jitlink -noexec -check %s %t.32.o
+# RUN: yaml2obj -DELFCLASS=ELFCLASS64 -o %t.64.o %s
+# RUN: llvm-jitlink -noexec -check %s %t.64.o
+
+### Compiled from the following code with -mattr=+relax to force relocations for
+### address_range and DW_CFA_advance_loc (both needed for .balign).
+## 	.text
+## 	.globl	main
+## 	.p2align	1
+## 	.type	main,@function
+## main:
+## 	.cfi_startproc
+##     .balign 8
+## 	addi	sp, sp, -16
+## cfa_advance_loc:
+## 	.cfi_def_cfa_offset 16
+##     nop
+## main_end:
+## 	.size	main, main_end-main
+## 	.cfi_endproc
+
+--- !ELF
+FileHeader:
+  Class:           [[ELFCLASS]]
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_RISCV
+  SectionHeaderStringTable: .strtab
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x8
+    Content:         13000000130101FF13000000
+  - Name:            .eh_frame
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC ]
+    AddressAlign:    0x8
+    Content:         1000000000000000017A5200017801011B0C02001000000018000000000000000000000000400E10
+  - Name:            .rela.text
+    Type:            SHT_RELA
+    Flags:           [ SHF_INFO_LINK ]
+    Link:            .symtab
+    AddressAlign:    0x8
+    Info:            .text
+    Relocations:
+      - Type:            R_RISCV_ALIGN
+        Addend:          4
+  - Name:            .rela.eh_frame
+    Type:            SHT_RELA
+    Flags:           [ SHF_INFO_LINK ]
+    Link:            .symtab
+    AddressAlign:    0x8
+    Info:            .eh_frame
+    Relocations:
+      - Offset:          0x1C
+        Symbol:          main
+        Type:            R_RISCV_32_PCREL
+      - Offset:          0x20
+        Symbol:          main_end
+        Type:            R_RISCV_ADD32
+      - Offset:          0x20
+        Symbol:          main
+        Type:            R_RISCV_SUB32
+      - Offset:          0x25
+        Symbol:          cfa_advance_loc
+        Type:            R_RISCV_SET6
+      - Offset:          0x25
+        Symbol:          main
+        Type:            R_RISCV_SUB6
+  - Type:            SectionHeaderTable
+    Sections:
+      - Name:            .strtab
+      - Name:            .text
+      - Name:            .rela.text
+      - Name:            .eh_frame
+      - Name:            .rela.eh_frame
+      - Name:            .symtab
+Symbols:
+  - Name:            cfa_advance_loc
+    Section:         .text
+    Value:           0x8
+  - Name:            main_end
+    Section:         .text
+    Value:           0xC
+  - Name:            main
+    Type:            STT_FUNC
+    Section:         .text
+    Binding:         STB_GLOBAL
+    Size:            0xC
+  - Name:            eh_frame
+    Type:            STT_SECTION
+    Binding:         STB_GLOBAL
+    Section:         .eh_frame
+    Size:            0x28
+...
+
+## CIE_pointer
+# jitlink-check: *{4}(eh_frame + 0x1c) = main - (eh_frame + 0x1c)
+## address_range
+# jitlink-check: *{4}(eh_frame + 0x20) = main_end - main
+## DW_CFA_advance_loc
+# jitlink-check: (*{1}(eh_frame + 0x25)) & 0x3f = cfa_advance_loc - main