[PULL 7/7] tcg/optimize: Fix TCG_COND_TST* simplification of setcond2

[Richard Henderson]

Argument ordering for setcond2 is:

  output, a_low, a_high, b_low, b_high, cond

The test is supposed to be against b_low, not a_high.

Cc: qemu-stable@nongnu.org
Fixes: ceb9ee06b71 ("tcg/optimize: Handle TCG_COND_TST{EQ,NE}")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2413
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240701024623.1265028-1-richard.henderson@linaro.org>
---
 tcg/optimize.c                   |  2 +-
 tests/tcg/x86_64/test-2413.c     | 30 ++++++++++++++++++++++++++++++
 tests/tcg/x86_64/Makefile.target |  2 ++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 tests/tcg/x86_64/test-2413.c

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 8886f7037a..ba16ec27e2 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -2384,7 +2384,7 @@ static bool fold_setcond2(OptContext *ctx, TCGOp *op)
 
     case TCG_COND_TSTEQ:
     case TCG_COND_TSTNE:
-        if (arg_is_const_val(op->args[2], 0)) {
+        if (arg_is_const_val(op->args[3], 0)) {
             goto do_setcond_high;
         }
         if (arg_is_const_val(op->args[4], 0)) {
diff --git a/tests/tcg/x86_64/test-2413.c b/tests/tcg/x86_64/test-2413.c
new file mode 100644
index 0000000000..456e5332fc
--- /dev/null
+++ b/tests/tcg/x86_64/test-2413.c
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright 2024 Linaro, Ltd. */
+/* See https://gitlab.com/qemu-project/qemu/-/issues/2413 */
+
+#include <assert.h>
+
+void test(unsigned long *a, unsigned long *d, unsigned long c)
+{
+    asm("xorl %%eax, %%eax\n\t"
+        "xorl %%edx, %%edx\n\t"
+        "testb $0x20, %%cl\n\t"
+        "sete %%al\n\t"
+        "setne %%dl\n\t"
+        "shll %%cl, %%eax\n\t"
+        "shll %%cl, %%edx\n\t"
+        : "=a"(*a), "=d"(*d)
+        : "c"(c));
+}
+
+int main(void)
+{
+    unsigned long a, c, d;
+
+    for (c = 0; c < 64; c++) {
+        test(&a, &d, c);
+        assert(a == (c & 0x20 ? 0 : 1u << (c & 0x1f)));
+        assert(d == (c & 0x20 ? 1u << (c & 0x1f) : 0));
+    }
+    return 0;
+}
diff --git a/tests/tcg/x86_64/Makefile.target b/tests/tcg/x86_64/Makefile.target
index 5fedf22117..eda9bd7396 100644
--- a/tests/tcg/x86_64/Makefile.target
+++ b/tests/tcg/x86_64/Makefile.target
@@ -8,6 +8,8 @@
 
 include $(SRC_PATH)/tests/tcg/i386/Makefile.target
 
+X86_64_TESTS += test-2413
+
 ifeq ($(filter %-linux-user, $(TARGET)),$(TARGET))
 X86_64_TESTS += vsyscall
 X86_64_TESTS += noexec
-- 
2.34.1