08ac3b39d4
Fixes #146973 When an object with alignment requirements is placed on the stack, this causes a stack realignment which causes AArch64 to use x19 to refer to objects on the stack as there may be a gap between local variables and the Stack Pointer. This causes issues with the MSVC C++ exception personality as the offset to the catch object recorded in the handler table no longer matches the object being used in the catch block itself. The fix for this is to place catch objects into the fixed object area.
101 lines
3.0 KiB
LLVM
101 lines
3.0 KiB
LLVM
; RUN: llc %s --mtriple=aarch64-pc-windows-msvc -o - | FileCheck %s
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; Tests the fixed object layouts when two catchpads re-use the same stack
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; allocation for this catch objects.
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; Generated from this C++ code, with modifications to the IR (see comments in
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; IR):
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; https://godbolt.org/z/9qv5Yn68j
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; > clang --target=aarch64-pc-windows-msvc test.cpp
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; ```
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; extern "C" void boom();
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; extern "C" int calls_boom();
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; {
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; try { boom(); }
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; catch (int& i) { return i; }
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; catch (long& l) { return l; }
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; return 0;
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; }
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; ```
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; Only need 48 bytes on the stack, not 64.
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; CHECK-LABEL: calls_boom:
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; CHECK: sub sp, sp, #48
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; CHECK: .seh_stackalloc 48
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; Both the catch blocks load from the same address.
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; CHECK-LABEL: "?catch$3@?0?calls_boom@4HA":
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; CHECK: ldr x8, [x29, #24]
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; CHECK-LABEL: "?catch$4@?0?calls_boom@4HA":
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; CHECK: ldr x8, [x29, #24]
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; There's enough space for the UnwindHelp to be at -16 instead of -32
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; CHECK-LABEL: $cppxdata$calls_boom:
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; CHECK: .word -16 // UnwindHelp
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; Both catches have the same object offset.
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; CHECK-LABEL: $handlerMap$0$calls_boom:
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; CHECK: .word -8 // CatchObjOffset
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; CHECK-NEXT: .word "?catch$3@?0?calls_boom@4HA"@IMGREL // Handler
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; CHECK: .word -8 // CatchObjOffset
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; CHECK-NEXT: .word "?catch$4@?0?calls_boom@4HA"@IMGREL // Handler
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%rtti.TypeDescriptor2 = type { ptr, ptr, [3 x i8] }
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$"??_R0H@8" = comdat any
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$"??_R0J@8" = comdat any
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@"??_7type_info@@6B@" = external constant ptr
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@"??_R0H@8" = linkonce_odr global %rtti.TypeDescriptor2 { ptr @"??_7type_info@@6B@", ptr null, [3 x i8] c".H\00" }, comdat
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@"??_R0J@8" = linkonce_odr global %rtti.TypeDescriptor2 { ptr @"??_7type_info@@6B@", ptr null, [3 x i8] c".J\00" }, comdat
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define dso_local i32 @calls_boom() personality ptr @__CxxFrameHandler3 {
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entry:
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%retval = alloca i32, align 4
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; MODIFICATION: Remove unusued alloca
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; %l = alloca ptr, align 8
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%i = alloca ptr, align 8
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invoke void @boom()
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to label %invoke.cont unwind label %catch.dispatch
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catch.dispatch:
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%0 = catchswitch within none [label %catch1, label %catch] unwind to caller
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catch1:
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%1 = catchpad within %0 [ptr @"??_R0H@8", i32 8, ptr %i]
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%2 = load ptr, ptr %i, align 8
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%3 = load i32, ptr %2, align 4
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store i32 %3, ptr %retval, align 4
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catchret from %1 to label %catchret.dest2
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catch:
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; MODIFICATION: Use %i instead of %l
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%4 = catchpad within %0 [ptr @"??_R0J@8", i32 8, ptr %i]
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%5 = load ptr, ptr %i, align 8
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%6 = load i32, ptr %5, align 4
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store i32 %6, ptr %retval, align 4
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catchret from %4 to label %catchret.dest
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invoke.cont:
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br label %try.cont
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catchret.dest:
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br label %return
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catchret.dest2:
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br label %return
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try.cont:
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store i32 0, ptr %retval, align 4
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br label %return
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return:
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%7 = load i32, ptr %retval, align 4
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ret i32 %7
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}
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declare dso_local void @boom() #1
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declare dso_local i32 @__CxxFrameHandler3(...)
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