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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Incorrect call site values for parameters produced by MOVZXi on AArch64"
href="https://bugs.llvm.org/show_bug.cgi?id=43975">43975</a>
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<th>Summary</th>
<td>Incorrect call site values for parameters produced by MOVZXi on AArch64
</td>
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<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>DebugInfo
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>david.stenberg@ericsson.com
</td>
</tr>
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<th>CC</th>
<td>jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com
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<pre>Reproduced on 636412bf31fc4285d63faeea67e4d71e44e3799c.
Compiling the following code:
#include <stdint.h>
extern void call1(int64_t);
extern void call2(int64_t);
extern void call3(int64_t);
extern void call4(int64_t);
void caller() {
call1(UINT64_C(1) << 0);
call2(UINT64_C(1) << 16);
call3(UINT64_C(1) << 32);
call4(UINT64_C(1) << 48);
}
using the following command:
clang movz.c --target=aarch64 -O1 -g -Xclang -femit-debug-entry-values -c
gives the following call site entries for the calls to call[1-4]:
$ llvm-dwarfdump movz.o | grep -E '(abstract_origin|call_site_value)'
DW_AT_abstract_origin (0x0000002a "call1")
DW_AT_GNU_call_site_value (DW_OP_lit1)
DW_AT_abstract_origin (0x0000003e "call2")
DW_AT_GNU_call_site_value (DW_OP_constu 0x10000)
DW_AT_abstract_origin (0x0000004b "call3")
DW_AT_GNU_call_site_value (DW_OP_lit1)
DW_AT_abstract_origin (0x00000058 "call4")
DW_AT_GNU_call_site_value (DW_OP_constu 0x10000)
As seen, the values passed to call3 and call4 are incorrect; 1 instead of
0x100000000 and 0x10000 instead of 0x1000000000000.
The issue seems to be that in AArch64InstrInfo::describeLoadedValue() a 32-bit
shift is used when calculating the immediate:
5762 int Immediate = MI.getOperand(1).getImm();
5763 int Shift = MI.getOperand(2).getImm();
5764 return ParamLoadedValue(MachineOperand::CreateImm(Immediate <<
Shift),
5765 nullptr);</pre>
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