add new target-specific abi0 pass

The general idea is to give abis a
chance to talk before we've done all
the optimizations. Currently, all
targets eliminate {par,arg,ret}{sb,ub,...}
during this pass. The forthcoming
arm64_apple will, however, insert
proper extensions during abi0.

Moving forward abis can, for example,
lower small-aggregates passing there
so that memory optimizations can
interact better with function calls.

1 files changed, 25 insertions, 0 deletions

diff --git a/abi.c b/abi.c
new file mode 100644
index 0000000..9c83497
--- /dev/null
+++ b/abi.c
@@ -0,0 +1,25 @@
+#include "all.h"
+
+/* eliminate sub-word abi op
+ * variants for targets that
+ * treat char/short/... as
+ * words with arbitrary high
+ * bits
+ */
+void
+elimsb(Fn *fn)
+{
+	Blk *b;
+	Ins *i;
+
+	for (b=fn->start; b; b=b->link) {
+		for (i=b->ins; i<&b->ins[b->nins]; i++) {
+			if (isargbh(i->op))
+				i->op = Oarg;
+			if (isparbh(i->op))
+				i->op = Opar;
+		}
+		if (isretbh(b->jmp.type))
+			b->jmp.type = Jretw;
+	}
+}