[AsmPrinter] Fix Crash when Emitting Global Constant of small bit width when targeting Big Endian arch

[HazyFish]

Summary

For Big Endian, the function emitGlobalConstantLargeInt tries to right shift Realigned by an amount ExtraBitSize in place. However, if the constant to emit has a bit width less than 64 and the bit width is not a multiple of 8, the shift amount will be greater than the bit width of Realigned, which causes assertion error described in issue issue #59055.

This patch fixes the issue by avoiding right shift when bit width is under 64 to avoid the assertion error.

[efriedma]

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

3273

Please upload patches with context (use "git diff -U100000", or use Arcanist).

Maybe it's clearer to just write:

if (BitWidth >= 64)
  Realigned.lshrInPlace(ExtraBitsSize);

llvm/test/CodeGen/AArch64/aarch64_be-global-const.ll

6

If you can't make update_llc_test_checks.py generate something appropriate, please write an appropriate CHECK line by hand.

Maybe it makes sense to just add a RUN line to an existing test, instead of adding a separate test file?

[HazyFish]

Address feedback

[HazyFish]

Align with upstream

[Peter]

arc land

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

       ExtraBitsSize = alignTo(ExtraBitsSize, 8);
       ExtraBits = Realigned.getRawData()[0] &
         (((uint64_t)-1) >> (64 - ExtraBitsSize));
+
+      if (BitWidth < 64)
+        Realigned = Realigned.zext(ExtraBitsSize);
       Realigned.lshrInPlace(ExtraBitsSize);
     } else
       ExtraBits = Realigned.getRawData()[BitWidth / 64];

llvm/test/CodeGen/AArch64/aarch64_be-global-const.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=aarch64_be < %s | FileCheck %s
+
+@G = global <4 x i1> <i1 true, i1 false, i1 true, i1 true>
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; CHECK: {{.*}}