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+id = 2865
+title = "loongarch64: wrong implementation of `xvldi` instruction"
+state = "closed"
+created_at = "2025-03-16T17:39:40.541Z"
+closed_at = "2025-03-17T12:59:28.649Z"
+labels = ["target: loongarch"]
+url = "https://gitlab.com/qemu-project/qemu/-/issues/2865"
+host-os = "Debian"
+host-arch = "loongarch64 (default one)"
+qemu-version = "qemu-loongarch64 version 9.2.2 (Debian 1:9.2.2+ds-1+b2)"
+guest-os = "n/a"
+guest-arch = "loongarch64 (default one)"
+description = """Consider this sample program.
+
+```c++
+#include <cstdio>
+#include <cstdint>
+#include <lsxintrin.h>
+#include <lasxintrin.h>
+
+void dump_u32(__m256i x) {
+    uint32_t tmp[32/4];
+    __lasx_xvst(x, tmp, 0);
+    putchar('[');
+    for (int i=0; i < 32/4; i++) {
+        if (i > 0) {
+            putchar(' ');
+        }
+
+        printf("%08x", tmp[i]);
+    }
+    puts("]");
+}
+
+int main() {
+    __m256i const1 = __lasx_xvldi(-3832);
+    dump_u32(const1);
+}
+```
+
+The magic constants here means: replicate in 32-bit words a byte (0x4) shifted left by 8. We should have a vector of words 0x800, and indeed, the program run on a real hardware prints expected:
+
+```
+[00000800 00000800 00000800 00000800 00000800 00000800 00000800 00000800]
+```
+
+The same program run under Qemu prints:
+
+```
+[08000800 00000000 08000800 00000000 08000800 00000000 08000800 00000000]
+```"""
+reproduce = "n/a"
+additional = """I grabbed the latest sources, it seems there's bug in `target/loongarch/tcg/insn_trans/trans_vec.c.inc`, in function `vldi_get_value`.
+
+```c
+    case 1:
+        /* data: {2{16'0, imm[7:0], 8'0}} */
+        data = (t << 24) | (t << 8);
+        break;
+```
+
+There should be `(t << (8+32)) | t << 8`."""