[LoongArch] Don't left shift negative value

[vitalybuka]

Fixed another UB from #106332.

Detected here https://lab.llvm.org/buildbot/#/builders/169/builds/2662

[llvmbot]

@llvm/pr-subscribers-backend-loongarch

Author: Vitaly Buka (vitalybuka)

Changes

Fixed another UB from #106332.

---

Full diff: https://github.com/llvm/llvm-project/pull/106812.diff

1 Files Affected:

• (modified) llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMatInt.cpp (+2-2)

diff --git a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMatInt.cpp b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMatInt.cpp
index a7823470382756..08e5ccc7bc0be5 100644
--- a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMatInt.cpp
+++ b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMatInt.cpp
@@ -82,9 +82,9 @@ LoongArchMatInt::InstSeq LoongArchMatInt::generateInstSeq(int64_t Val) {
       TmpVal1 = Insts[1].Imm;
       if (N == 3)
         break;
-      TmpVal2 = Insts[3].Imm << 52 | TmpVal1;
+      TmpVal2 = static_cast<uint64_t>(Insts[3].Imm) << 52 | TmpVal1;
     }
-    TmpVal1 |= Insts[0].Imm << 12;
+    TmpVal1 |= static_cast<uint64_t>(Insts[0].Imm) << 12;
     break;
   case LoongArch::ORI:
   case LoongArch::ADDI_W:

[wangleiat]

Thanks again.