performance: 0.915 semantic: 0.886 other: 0.830 graphic: 0.817 device: 0.770 debug: 0.745 PID: 0.661 permissions: 0.647 network: 0.646 vnc: 0.567 files: 0.558 socket: 0.540 KVM: 0.539 boot: 0.473 RISCV64 32-bit AMOs incorrectly simulated Version: qemu-riscv64 version 4.2.1 (Debian 1:4.2-3ubuntu6.14) test: amomaxu.w a0, a1, (a0) ret int32_t* value = -7; EXPECT_EQ(-7, test(&value, -11)); EXPECT_EQ(-7, value); // FAIL, saw -11 EXPECT_EQ(-7, test(&value, -7)); EXPECT_EQ(-7, value); // FAIL, raw -11 EXPECT_EQ(-7, test(&value, -4)); EXPECT_EQ(-4, value); test: amomax.w a0, a1, (a0) ret int32_t* value = -7; EXPECT_EQ(-7, test(&value, -11)); EXPECT_EQ(-7, value); EXPECT_EQ(-7, test(&value, -7)); EXPECT_EQ(-7, value); EXPECT_EQ(-7, test(&value, -4)); EXPECT_EQ(-4, value); // FAIL, saw -7 I suspect that trans_amo_w should be using tcg_gen_atomic_fetch__i32 instead of tcg_gen_atomic_fetch__tl. Not as simple as _tl vs _i32. That suffix should be taking care of the sign-extension to _tl that happens after the operation. The size of the operation should be in the MO_TESL, which specifies target-endian signed "long" (32-bit). Will investigate further. Flushing out the report to something that compiles, the test case works for me using qemu 5.2.