tcg: Split trunc_shr_i32 opcode into extr[lh]_i64_i32
Rather than allow arbitrary shift+trunc, only concern ourselves
with low and high parts. This is all that was being used anyway.
Signed-off-by: Richard Henderson <rth@twiddle.net>
diff --git a/tcg/README b/tcg/README
index a22f251..34c0775 100644
--- a/tcg/README
+++ b/tcg/README
@@ -314,11 +314,17 @@
dest = (t1 & ~0x0f00) | ((t2 << 8) & 0x0f00)
-* trunc_shr_i64_i32 t0, t1, pos
+* extrl_i64_i32 t0, t1
-For 64-bit hosts only, right shift the 64-bit input T1 by POS and
-truncate to 32-bit output T0. Depending on the host, this may be
-a simple mov/shift, or may require additional canonicalization.
+For 64-bit hosts only, extract the low 32-bits of input T1 and place it
+into 32-bit output T0. Depending on the host, this may be a simple move,
+or may require additional canonicalization.
+
+* extrh_i64_i32 t0, t1
+
+For 64-bit hosts only, extract the high 32-bits of input T1 and place it
+into 32-bit output T0. Depending on the host, this may be a simple shift,
+or may require additional canonicalization.
********* Conditional moves
