Emit smaller exception tables for non-SJLJ mode.

* Use uleb128 for code offsets in the LSDA call site table.
* Omit the TTBase offset if the type table is empty.

This change can reduce the size of the DWARF/Itanium LSDA by about half.

Patch by Ryan Prichard!

llvm-svn: 324750

10 files changed, 39 insertions, 38 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
index d9db7832faa..094e4c9e19c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
@@ -374,15 +374,17 @@ void EHStreamer::emitExceptionTable() {
   computeCallSiteTable(CallSites, LandingPads, FirstActions);
 
   bool IsSJLJ = Asm->MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
-  bool HaveTTData = IsSJLJ ? (!TypeInfos.empty() || !FilterIds.empty()) : true;
+  unsigned CallSiteEncoding =
+      IsSJLJ ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_uleb128;
+  bool HaveTTData = !TypeInfos.empty() || !FilterIds.empty();
 
   // Type infos.
   MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
   unsigned TTypeEncoding;
 
   if (!HaveTTData) {
-    // For SjLj exceptions, if there is no TypeInfo, then we just explicitly say
-    // that we're omitting that bit.
+    // If there is no TypeInfo, then we just explicitly say that we're omitting
+    // that bit.
     TTypeEncoding = dwarf::DW_EH_PE_omit;
   } else {
     // Okay, we have actual filters or typeinfos to emit.  As such, we need to
@@ -450,7 +452,7 @@ void EHStreamer::emitExceptionTable() {
   // Emit the landing pad call site table.
   MCSymbol *CstBeginLabel = Asm->createTempSymbol("cst_begin");
   MCSymbol *CstEndLabel = Asm->createTempSymbol("cst_end");
-  Asm->EmitEncodingByte(dwarf::DW_EH_PE_udata4, "Call site");
+  Asm->EmitEncodingByte(CallSiteEncoding, "Call site");
   Asm->EmitLabelDifferenceAsULEB128(CstEndLabel, CstBeginLabel);
   Asm->OutStreamer->EmitLabel(CstBeginLabel);
 
@@ -518,23 +520,24 @@ void EHStreamer::emitExceptionTable() {
       // Offset of the call site relative to the start of the procedure.
       if (VerboseAsm)
         Asm->OutStreamer->AddComment(">> Call Site " + Twine(++Entry) + " <<");
-      Asm->EmitLabelDifference(BeginLabel, EHFuncBeginSym, 4);
+      Asm->EmitLabelDifferenceAsULEB128(BeginLabel, EHFuncBeginSym);
       if (VerboseAsm)
         Asm->OutStreamer->AddComment(Twine("  Call between ") +
                                      BeginLabel->getName() + " and " +
                                      EndLabel->getName());
-      Asm->EmitLabelDifference(EndLabel, BeginLabel, 4);
+      Asm->EmitLabelDifferenceAsULEB128(EndLabel, BeginLabel);
 
       // Offset of the landing pad relative to the start of the procedure.
       if (!S.LPad) {
         if (VerboseAsm)
           Asm->OutStreamer->AddComment("    has no landing pad");
-        Asm->OutStreamer->EmitIntValue(0, 4/*size*/);
+        Asm->EmitULEB128(0);
       } else {
         if (VerboseAsm)
           Asm->OutStreamer->AddComment(Twine("    jumps to ") +
                                        S.LPad->LandingPadLabel->getName());
-        Asm->EmitLabelDifference(S.LPad->LandingPadLabel, EHFuncBeginSym, 4);
+        Asm->EmitLabelDifferenceAsULEB128(S.LPad->LandingPadLabel,
+                                          EHFuncBeginSym);
       }
 
       // Offset of the first associated action record, relative to the start of
diff --git a/llvm/test/CodeGen/ARM/dwarf-eh.ll b/llvm/test/CodeGen/ARM/dwarf-eh.ll
index 07a07148edb..2731cbc24f4 100644
--- a/llvm/test/CodeGen/ARM/dwarf-eh.ll
+++ b/llvm/test/CodeGen/ARM/dwarf-eh.ll
@@ -64,8 +64,8 @@ declare void @__cxa_end_catch()
 ; CHECK: .cfi_personality 0,
 ; CHECK: .cfi_lsda 0,
 ; CHECK: @TType Encoding = absptr
-; CHECK: @ Call site Encoding = udata4
+; CHECK: @ Call site Encoding = uleb128
 ; CHECK-PIC: .cfi_personality 155,
 ; CHECK-PIC: .cfi_lsda 27,
 ; CHECK-PIC: @TType Encoding = indirect pcrel sdata4
-; CHECK-PIC: @ Call site Encoding = udata4
+; CHECK-PIC: @ Call site Encoding = uleb128
diff --git a/llvm/test/CodeGen/ARM/ehabi-handlerdata-nounwind.ll b/llvm/test/CodeGen/ARM/ehabi-handlerdata-nounwind.ll
index ec7a002996c..e38c69bc9c7 100644
--- a/llvm/test/CodeGen/ARM/ehabi-handlerdata-nounwind.ll
+++ b/llvm/test/CodeGen/ARM/ehabi-handlerdata-nounwind.ll
@@ -57,5 +57,5 @@ try.cont:
 ; CHECK:   .byte 255                     @ @LPStart Encoding = omit
 ; CHECK:   .byte 0                       @ @TType Encoding = absptr
 ; CHECK:   .uleb128 .Lttbase
-; CHECK:   .byte 3                       @ Call site Encoding = udata4
+; CHECK:   .byte 1                       @ Call site Encoding = uleb128
 ; CHECK:   .fnend
diff --git a/llvm/test/CodeGen/ARM/ehabi-handlerdata.ll b/llvm/test/CodeGen/ARM/ehabi-handlerdata.ll
index af5728bf831..2f4354983ca 100644
--- a/llvm/test/CodeGen/ARM/ehabi-handlerdata.ll
+++ b/llvm/test/CodeGen/ARM/ehabi-handlerdata.ll
@@ -52,9 +52,9 @@ try.cont:
 ; CHECK:   .byte 255                     @ @LPStart Encoding = omit
 ; CHECK:   .byte 0                       @ @TType Encoding = absptr
 ; CHECK:   .uleb128 .Lttbase
-; CHECK:   .byte 3                       @ Call site Encoding = udata4
+; CHECK:   .byte 1                       @ Call site Encoding = uleb128
 ; CHECK:   .uleb128 .Lcst_end
-; CHECK:   .long
-; CHECK:   .long
-; CHECK:   .long
+; CHECK:   .uleb128
+; CHECK:   .uleb128
+; CHECK:   .uleb128
 ; CHECK:   .fnend
diff --git a/llvm/test/CodeGen/X86/eh-label.ll b/llvm/test/CodeGen/X86/eh-label.ll
index d349174f95b..26c3f37992e 100644
--- a/llvm/test/CodeGen/X86/eh-label.ll
+++ b/llvm/test/CodeGen/X86/eh-label.ll
@@ -20,5 +20,5 @@ bb2:
   ret void
 
 ; CHECK: [[END:.Lfunc_end.*]]:
-; CHECK: .long	[[END]]-
+; CHECK: .uleb128	[[END]]-
 }
diff --git a/llvm/test/CodeGen/X86/eh-unknown.ll b/llvm/test/CodeGen/X86/eh-unknown.ll
index f9f3696a869..28b5a8ada30 100644
--- a/llvm/test/CodeGen/X86/eh-unknown.ll
+++ b/llvm/test/CodeGen/X86/eh-unknown.ll
@@ -22,14 +22,12 @@ entry:
 ; CHECK: .seh_handlerdata
 ; CHECK: .Lexception0:
 ; CHECK:  .byte   255                     # @LPStart Encoding = omit
-; CHECK:  .byte   0                       # @TType Encoding = absptr
-; CHECK:  .uleb128 .Lttbase0-.Lttbaseref0
-; CHECK:  .Lttbaseref0:
-; CHECK:  .byte   3                       # Call site Encoding = udata4
+; CHECK:  .byte   255                     # @TType Encoding = omit
+; CHECK:  .byte   1                       # Call site Encoding = uleb128
 ; CHECK:  .uleb128 .Lcst_end0-.Lcst_begin0
 ; CHECK:  .Lcst_begin0:
-; CHECK:  .long .Lfunc_begin0-.Lfunc_begin0 # >> Call Site 1 <<
-; CHECK:  .long .Lfunc_end0-.Lfunc_begin0 #   Call between .Lfunc_begin0 and .Lfunc_end0
-; CHECK:  .long   0                       #     has no landing pad
+; CHECK:  .uleb128 .Lfunc_begin0-.Lfunc_begin0 # >> Call Site 1 <<
+; CHECK:  .uleb128 .Lfunc_end0-.Lfunc_begin0 #   Call between .Lfunc_begin0 and .Lfunc_end0
+; CHECK:  .byte   0                       #     has no landing pad
 ; CHECK:  .byte   0                       #   On action: cleanup
 ; CHECK:  .Lcst_end0:
diff --git a/llvm/test/CodeGen/X86/patchpoint-invoke.ll b/llvm/test/CodeGen/X86/patchpoint-invoke.ll
index df273777675..d888fb5e4cf 100644
--- a/llvm/test/CodeGen/X86/patchpoint-invoke.ll
+++ b/llvm/test/CodeGen/X86/patchpoint-invoke.ll
@@ -36,12 +36,12 @@ threw:
 ; CHECK-NEXT: .byte 3
 ; CHECK-NEXT: .uleb128 .Lttbase{{[0-9]+}}-[[TTBASEREF:.Lttbaseref[0-9]+]]
 ; CHECK-NEXT: [[TTBASEREF]]:
-; CHECK-NEXT: .byte 3
+; CHECK-NEXT: .byte 1
 ; CHECK-NEXT: .uleb128 .Lcst_end{{[0-9]+}}-[[CST_BEGIN:.Lcst_begin[0-9]+]]
 ; CHECK-NEXT: [[CST_BEGIN]]:
 ; Verify that the unwind data covers the entire patchpoint region:
-; CHECK-NEXT: .long .Ltmp0-[[FUNC_BEGIN]]
-; CHECK-NEXT: .long [[PP_END]]-.Ltmp0
+; CHECK-NEXT: .uleb128 .Ltmp0-[[FUNC_BEGIN]]
+; CHECK-NEXT: .uleb128 [[PP_END]]-.Ltmp0
 
 
 ; Verify that the stackmap section got emitted:
diff --git a/llvm/test/CodeGen/X86/push-cfi-obj.ll b/llvm/test/CodeGen/X86/push-cfi-obj.ll
index 33291ec3318..8b3c3adec2e 100644
--- a/llvm/test/CodeGen/X86/push-cfi-obj.ll
+++ b/llvm/test/CodeGen/X86/push-cfi-obj.ll
@@ -11,7 +11,7 @@
 ; LINUX-NEXT:      SHF_ALLOC (0x2)
 ; LINUX-NEXT:    ]
 ; LINUX-NEXT:    Address: 0x0
-; LINUX-NEXT:    Offset: 0x68
+; LINUX-NEXT:    Offset: 0x5C
 ; LINUX-NEXT:    Size: 64
 ; LINUX-NEXT:    Link: 0
 ; LINUX-NEXT:    Info: 0
diff --git a/llvm/test/CodeGen/X86/statepoint-invoke.ll b/llvm/test/CodeGen/X86/statepoint-invoke.ll
index 784b932addc..12a122680a2 100644
--- a/llvm/test/CodeGen/X86/statepoint-invoke.ll
+++ b/llvm/test/CodeGen/X86/statepoint-invoke.ll
@@ -38,8 +38,8 @@ exceptional_return:
   ret i64 addrspace(1)* %obj1.relocated1
 }
 ; CHECK-LABEL: GCC_except_table{{[0-9]+}}:
-; CHECK: .long  .Ltmp{{[0-9]+}}-.Ltmp{{[0-9]+}}
-; CHECK: .long  .Ltmp{{[0-9]+}}-.Lfunc_begin{{[0-9]+}}
+; CHECK: .uleb128  .Ltmp{{[0-9]+}}-.Ltmp{{[0-9]+}}
+; CHECK: .uleb128  .Ltmp{{[0-9]+}}-.Lfunc_begin{{[0-9]+}}
 ; CHECK: .byte  0
 ; CHECK: .p2align 4
 
@@ -68,8 +68,8 @@ exceptional_return:
   ret i64 addrspace(1)* %obj.relocated
 }
 ; CHECK-LABEL: GCC_except_table{{[0-9]+}}:
-; CHECK: .long .Ltmp{{[0-9]+}}-.Ltmp{{[0-9]+}}
-; CHECK: .long .Ltmp{{[0-9]+}}-.Lfunc_begin{{[0-9]+}}
+; CHECK: .uleb128 .Ltmp{{[0-9]+}}-.Ltmp{{[0-9]+}}
+; CHECK: .uleb128 .Ltmp{{[0-9]+}}-.Lfunc_begin{{[0-9]+}}
 ; CHECK: .byte 0
 ; CHECK: .p2align 4
 
diff --git a/llvm/test/CodeGen/XCore/exception.ll b/llvm/test/CodeGen/XCore/exception.ll
index 988001043d0..48845a5471e 100644
--- a/llvm/test/CodeGen/XCore/exception.ll
+++ b/llvm/test/CodeGen/XCore/exception.ll
@@ -107,16 +107,16 @@ Exit:
 ; CHECK: .byte  0
 ; CHECK: .uleb128 [[TTBASE:.Lttbase[0-9]+]]-[[TTBASEREF:.Lttbaseref[0-9]+]]
 ; CHECK: [[TTBASEREF]]:
-; CHECK: .byte  3
+; CHECK: .byte  1
 ; CHECK: .uleb128 [[CST_END:.Lcst_end[0-9]+]]-[[CST_BEGIN:.Lcst_begin[0-9]+]]
 ; CHECK: [[CST_BEGIN]]:
-; CHECK: .long [[PRE_G]]-[[START]]
-; CHECK: .long [[POST_G]]-[[PRE_G]]
-; CHECK: .long [[LANDING]]-[[START]]
+; CHECK: .uleb128 [[PRE_G]]-[[START]]
+; CHECK: .uleb128 [[POST_G]]-[[PRE_G]]
+; CHECK: .uleb128 [[LANDING]]-[[START]]
 ; CHECK: .byte 5
-; CHECK: .long [[POST_G]]-[[START]]
-; CHECK: .long [[END]]-[[POST_G]]
-; CHECK: .long 0
+; CHECK: .uleb128 [[POST_G]]-[[START]]
+; CHECK: .uleb128 [[END]]-[[POST_G]]
+; CHECK: .byte 0
 ; CHECK: .byte 0
 ; CHECK: [[CST_END]]:
 ; CHECK: .byte 0