[llvm-branch-commits] [llvm] 7a91dad - [llvm-readobj] [ARMWinEH] Clearly print an invalid case of packed unwind info as such

[Martin Storsjö via llvm-branch-commits]

Author: Martin Storsjö
Date: 2021-01-08T10:04:44+02:00
New Revision: 7a91dad9e5fa17ed31484ea7f264363b9b821861

URL: https://github.com/llvm/llvm-project/commit/7a91dad9e5fa17ed31484ea7f264363b9b821861
DIFF: https://github.com/llvm/llvm-project/commit/7a91dad9e5fa17ed31484ea7f264363b9b821861.diff

LOG: [llvm-readobj] [ARMWinEH] Clearly print an invalid case of packed unwind info as such

As the actual windows unwinder doesn't support this case, don't
pretend that it is supported when dumping the generated unwind info
either, even if it would be possible to interpret it as something
sensible.

This should reduce the risk of us emitting such a case in code
(although it's unlikely as long as the unwind info is generated
through the SEH opcodes, as the opcodes can't describe this case).

Differential Revision: https://reviews.llvm.org/D91529

Added: 
    

Modified: 
    llvm/test/tools/llvm-readobj/COFF/arm64-packed-unwind.s
    llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/test/tools/llvm-readobj/COFF/arm64-packed-unwind.s b/llvm/test/tools/llvm-readobj/COFF/arm64-packed-unwind.s
index f8c4d5e3074f..155c292e1649 100644
--- a/llvm/test/tools/llvm-readobj/COFF/arm64-packed-unwind.s
+++ b/llvm/test/tools/llvm-readobj/COFF/arm64-packed-unwind.s
@@ -139,7 +139,7 @@
 // CHECK-NEXT:     FrameSize: 32
 // CHECK-NEXT:     Prologue [
 // CHECK-NEXT:       sub sp, sp, #16
-// CHECK-NEXT:       stp x19, lr, [sp, #-16]!
+// CHECK-NEXT:       INVALID!
 // CHECK-NEXT:       end
 // CHECK-NEXT:     ]
 // CHECK-NEXT:   }

diff  --git a/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp b/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
index 46a949b99045..5995a09514c8 100644
--- a/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
+++ b/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
@@ -1223,10 +1223,12 @@ bool Decoder::dumpPackedARM64Entry(const object::COFFObjectFile &COFF,
     if (I == (RF.RegI() + 1) / 2 - 1 && RF.RegI() % 2 == 1) {
       // The last register, an odd register without a pair
       if (RF.CR() == 1) {
-        if (I == 0) // If this is the only register pair
-          SW.startLine() << format("stp x%d, lr, [sp, #-%d]!\n", 19 + 2 * I,
-                                   SavSZ);
-        else
+        if (I == 0) { // If this is the only register pair
+          // CR=1 combined with RegI=1 doesn't map to a documented case;
+          // it doesn't map to any regular unwind info opcode, and the
+          // actual unwinder doesn't support it.
+          SW.startLine() << "INVALID!\n";
+        } else
           SW.startLine() << format("stp x%d, lr, [sp, #%d]\n", 19 + 2 * I,
                                    16 * I);
       } else {