Add an option that allows one to "decode" the LSDA.

The LSDA is a bit difficult for the non-initiated to read. Even with comments,
it's not always clear what's going on. This wraps the ASM streamer in a class
that retains the LSDA and then emits a human-readable description of what's
going on in it.

So instead of having to make sense of:

Lexception1:
        .byte   255
        .byte   155
        .byte   168
        .space  1
        .byte   3
        .byte   26
Lset0 = Ltmp7-Leh_func_begin1
      .long     Lset0
Lset1 = Ltmp812-Ltmp7
      .long     Lset1
Lset2 = Ltmp913-Leh_func_begin1
      .long     Lset2
      .byte     3
Lset3 = Ltmp812-Leh_func_begin1
      .long     Lset3
Lset4 = Leh_func_end1-Ltmp812
      .long     Lset4
      .long     0
      .byte     0
      .byte     1
      .byte     0
      .byte     2
      .byte     125
      .long     __ZTIi@GOTPCREL+4
      .long     __ZTIPKc@GOTPCREL+4

you can read this instead:

## Exception Handling Table: Lexception1
##  @LPStart Encoding: omit
##    @TType Encoding: indirect pcrel sdata4
##        @TType Base: 40 bytes
## @CallSite Encoding: udata4
## @Action Table Size: 26 bytes

## Action 1:
##   A throw between Ltmp7 and Ltmp812 jumps to Ltmp913 on an exception.
##     For type(s):  __ZTIi@GOTPCREL+4 __ZTIPKc@GOTPCREL+4
## Action 2:
##   A throw between Ltmp812 and Leh_func_end1 does not have a landing pad.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133286 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 5 deletions

diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index c05a9251dc..6f017136c2 100644
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -547,6 +547,9 @@ namespace llvm {
   ///
   /// \param ShowInst - Whether to show the MCInst representation inline with
   /// the assembly.
+  ///
+  /// \param DecodeLSDA - If true, emit comments that translates the LSDA into a
+  /// human readable format. Only usable with CFI.
   MCStreamer *createAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
                                 bool isVerboseAsm,
                                 bool useLoc,
@@ -554,7 +557,8 @@ namespace llvm {
                                 MCInstPrinter *InstPrint = 0,
                                 MCCodeEmitter *CE = 0,
                                 TargetAsmBackend *TAB = 0,
-                                bool ShowInst = false);
+                                bool ShowInst = false,
+                                bool DecodeLSDA = false);
 
   /// createMachOStreamer - Create a machine code streamer which will generate
   /// Mach-O format object files.
diff --git a/include/llvm/Target/TargetRegistry.h b/include/llvm/Target/TargetRegistry.h
index a464822893..0bec8bc1ec 100644
--- a/include/llvm/Target/TargetRegistry.h
+++ b/include/llvm/Target/TargetRegistry.h
@@ -47,7 +47,8 @@ namespace llvm {
                                 MCInstPrinter *InstPrint,
                                 MCCodeEmitter *CE,
                                 TargetAsmBackend *TAB,
-                                bool ShowInst);
+                                bool ShowInst,
+                                bool DecodeLSDA);
 
   /// Target - Wrapper for Target specific information.
   ///
@@ -100,7 +101,8 @@ namespace llvm {
                                              MCInstPrinter *InstPrint,
                                              MCCodeEmitter *CE,
                                              TargetAsmBackend *TAB,
-                                             bool ShowInst);
+                                             bool ShowInst,
+                                             bool DecodeLSDA);
 
   private:
     /// Next - The next registered target in the linked list, maintained by the
@@ -334,10 +336,11 @@ namespace llvm {
                                   MCInstPrinter *InstPrint,
                                   MCCodeEmitter *CE,
                                   TargetAsmBackend *TAB,
-                                  bool ShowInst) const {
+                                  bool ShowInst,
+                                  bool DecodeLSDA) const {
       // AsmStreamerCtorFn is default to llvm::createAsmStreamer
       return AsmStreamerCtorFn(Ctx, OS, isVerboseAsm, useLoc, useCFI,
-                               InstPrint, CE, TAB, ShowInst);
+                               InstPrint, CE, TAB, ShowInst, DecodeLSDA);
     }
 
     /// @}