Conversation
Member
Author
Member
|
@llvm/pr-subscribers-llvm-binary-utilities Author: Martin Storsjö (mstorsjo) ChangesEven though the table for how to expand packed unwind info at [1] doesn't explicitly say this, this case is mentioned at [2] under the case "Only x19 saved": This was discussed and clarified at [3]. [1] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#packed-unwind-data Full diff: https://github.com/llvm/llvm-project/pull/169676.diff 2 Files Affected:
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 d9953ccc3f3d8..72e79b77a01ad 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 +139,8 @@
// CHECK-NEXT: FrameSize: 32
// CHECK-NEXT: Prologue [
// CHECK-NEXT: sub sp, sp, #16
-// CHECK-NEXT: INVALID!
+// CHECK-NEXT: stp x19, lr, [sp]
+// CHECK-NEXT: sub sp, sp, #16
// CHECK-NEXT: end
// CHECK-NEXT: ]
// CHECK-NEXT: }
diff --git a/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp b/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
index c6e409c63ef3a..8efd9f0182d53 100644
--- a/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
+++ b/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
@@ -1457,10 +1457,14 @@ bool Decoder::dumpPackedARM64Entry(const object::COFFObjectFile &COFF,
// The last register, an odd register without a pair
if (RF.CR() == 1) {
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";
+ // CR=1 combined with RegI=1 maps to a special case; there's
+ // no unwind info opcode that saves a GPR together with LR
+ // with writeback to sp (no save_lrpair_x).
+ // Instead, this case expands to two instructions; a preceding
+ // (in prologue execution order) "sub sp, sp, #16", followed
+ // by a regular "stp x19, lr, [sp]" (save_lrpair).
+ SW.startLine() << format("stp x%d, lr, [sp]\n", 19);
+ SW.startLine() << format("sub sp, sp, #16\n");
} else
SW.startLine() << format("stp x%d, lr, [sp, #%d]\n", 19 + 2 * I,
16 * I);
|
7d264fd to
009946b
Compare
mstorsjo
commented
Nov 26, 2025
…01 RegI=1
Even though the table for how to expand packed unwind info at [1]
doesn't explicitly say this, this case is mentioned at [2] under
the case "Only x19 saved":
sub sp,sp,llvm#16 // reg save area allocation*
stp x19,lr,[sp] // save x19, lr
sub sp,sp,#(framesz-16) // allocate the remaining local area
This was discussed and clarified at [3].
[1] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#packed-unwind-data
[2] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#arm64-stack-frame-layout
[3] llvm#169588 (comment)
009946b to
de454d0
Compare
| // (in prologue execution order) "sub sp, sp, #16", followed | ||
| // by a regular "stp x19, lr, [sp]" (save_lrpair). | ||
| SW.startLine() << format("stp x%d, lr, [sp]\n", 19); | ||
| SW.startLine() << format("sub sp, sp, #%d\n", SavSZ); |
Collaborator
There was a problem hiding this comment.
Should we print a warning if RegF() > 0?
Member
Author
There was a problem hiding this comment.
Nah, I don't think that's necessary. It is well defined and works correctly on the latest versions, so it makes sense to just dump it the right way, and we just avoid creating it.
efriedma-quic
approved these changes
Dec 1, 2025
| // (in prologue execution order) "sub sp, sp, #16", followed | ||
| // by a regular "stp x19, lr, [sp]" (save_lrpair). | ||
| SW.startLine() << format("stp x%d, lr, [sp]\n", 19); | ||
| SW.startLine() << format("sub sp, sp, #%d\n", SavSZ); |
kcloudy0717
pushed a commit
to kcloudy0717/llvm-project
that referenced
this pull request
Dec 4, 2025
…01 RegI=1 (llvm#169676) Even though the table for how to expand packed unwind info at [1] doesn't explicitly say this, this case is mentioned at [2] under the case "Only x19 saved": sub sp,sp,llvm#16 // reg save area allocation* stp x19,lr,[sp] // save x19, lr sub sp,sp,#(framesz-16) // allocate the remaining local area This was discussed and clarified at [3]. [1] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#packed-unwind-data [2] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#arm64-stack-frame-layout [3] llvm#169588 (comment)
honeygoyal
pushed a commit
to honeygoyal/llvm-project
that referenced
this pull request
Dec 9, 2025
…01 RegI=1 (llvm#169676) Even though the table for how to expand packed unwind info at [1] doesn't explicitly say this, this case is mentioned at [2] under the case "Only x19 saved": sub sp,sp,llvm#16 // reg save area allocation* stp x19,lr,[sp] // save x19, lr sub sp,sp,#(framesz-16) // allocate the remaining local area This was discussed and clarified at [3]. [1] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#packed-unwind-data [2] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#arm64-stack-frame-layout [3] llvm#169588 (comment)
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Even though the table for how to expand packed unwind info at [1] doesn't explicitly say this, this case is mentioned at [2] under the case "Only x19 saved":
This was discussed and clarified at [3].
[1] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#packed-unwind-data
[2] https://learn.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=msvc-170#arm64-stack-frame-layout
[3] #169588 (comment)