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

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 [[ #59055 | issue #59055 ]].

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

Reviewed By: Peter

Differential Revision: https://reviews.llvm.org/D138246

Author: HazyFish

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -3385,7 +3385,8 @@ static void emitGlobalConstantLargeInt(const ConstantInt *CI, AsmPrinter &AP) {
       ExtraBitsSize = alignTo(ExtraBitsSize, 8);
       ExtraBits = Realigned.getRawData()[0] &
         (((uint64_t)-1) >> (64 - ExtraBitsSize));
-      Realigned.lshrInPlace(ExtraBitsSize);
+      if (BitWidth >= 64)
+        Realigned.lshrInPlace(ExtraBitsSize);
     } else
       ExtraBits = Realigned.getRawData()[BitWidth / 64];
   }

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

@@ -0,0 +1,6 @@
+; RUN: llc -mtriple=aarch64_be < %s | FileCheck %s
+
+; CHECK-LABEL: G:
+; CHECK: .byte 11
+; CHECK: .size G, 1
+@G = global <4 x i1> <i1 true, i1 false, i1 true, i1 true>