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[06/12] tcg/optimize: Fold movcond with true and false values identical

Message ID 20240908022632.459477-7-richard.henderson@linaro.org
State Superseded
Headers show
Series tcg: Improve support for cmpsel_vec | expand

Commit Message

Richard Henderson Sept. 8, 2024, 2:26 a.m. UTC 
Fold "x = cond ? y : y" to "x = y".

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/optimize.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Philippe Mathieu-Daudé Sept. 10, 2024, 7 a.m. UTC | #1 
On 8/9/24 04:26, Richard Henderson wrote:
> Fold "x = cond ? y : y" to "x = y".
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   tcg/optimize.c | 5 +++++
>   1 file changed, 5 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
diff mbox series

Patch

diff --git a/tcg/optimize.c b/tcg/optimize.c
index ba16ec27e2..cf311790e0 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1851,6 +1851,11 @@  static bool fold_movcond(OptContext *ctx, TCGOp *op)
 {
     int i;
 
+    /* If true and false values are the same, eliminate the cmp. */
+    if (args_are_copies(op->args[3], op->args[4])) {
+        return tcg_opt_gen_mov(ctx, op, op->args[0], op->args[3]);
+    }
+
     /*
      * Canonicalize the "false" input reg to match the destination reg so
      * that the tcg backend can implement a "move if true" operation.