Lower stacksave and restore intrinsics.

crosstest/test_stacksave.c

Index: crosstest/test_stacksave.c
diff --git a/crosstest/test_stacksave.c b/crosstest/test_stacksave.c
new file mode 100644
index 0000000000000000000000000000000000000000..b0e9b5e2be9f943c314c511e79d1bfe8dea6b07a
--- /dev/null
+++ b/crosstest/test_stacksave.c
@@ -0,0 +1,76 @@
+//===- subzero/crosstest/test_stacksave.c - Implementation for tests ------===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This aims to test that C99's VLAs (which use stacksave/stackrestore
+// intrinsics) work fine.
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdint.h>
+
+#include "test_stacksave.h"
+DECLARE_TESTS()
+
+/* NOTE: This has 0 stacksaves, because the vla isn't in a loop,
+ * so the vla can just be freed by the epilogue.
+ */
+uint32_t test_basic_vla(uint32_t size, uint32_t start, uint32_t inc) {
+  uint32_t vla[size];
+  uint32_t mid = start + ((size - start) / 2);
+  for (uint32_t i = start; i < size; ++i) {
+    vla[i] = i + inc;
+  }
+  return (vla[start] << 2) + (vla[mid] << 1) + vla[size - 1];
+}
+
+static uint32_t __attribute__((noinline)) foo(uint32_t x) {
+  return x * x;
+}
+
+/* NOTE: This has 1 stacksave, because the vla is in a loop and should
+ * be freed before the next iteration.
+ */
+uint32_t test_vla_in_loop(uint32_t size, uint32_t start, uint32_t inc) {
+  uint32_t sum = 0;
+  for (uint32_t i = start; i < size; ++i) {
+    uint32_t size1 = size - i;
+    uint32_t vla[size1];
+    for (uint32_t j = 0; j < size1; ++j) {
+      /* Adjust stack again with a function call. */
+      vla[j] = foo(start * j + inc);
+    }
+    for (uint32_t j = 0; j < size1; ++j) {
+      sum += vla[j];
+    }
+  }
+  return sum;
+}
+
+uint32_t test_two_vlas_in_loops(uint32_t size, uint32_t start, uint32_t inc) {
+  uint32_t sum = 0;
+  for (uint32_t i = start; i < size; ++i) {
+    uint32_t size1 = size - i;
+    uint32_t vla1[size1];
+    for (uint32_t j = 0; j < size1; ++j) {
+      uint32_t size2 = size - j;
+      uint32_t start2 = 0;
+      uint32_t mid2 = size2 / 2;
+      uint32_t vla2[size2];
+      for (uint32_t k = start2; k < size2; ++k) {
+        /* Adjust stack again with a function call. */
+        vla2[k] = foo(start * k + inc);
+      }
+      vla1[j] = (vla2[start2] << 2) + (vla2[mid2] << 1) + vla2[size2 - 1];
+    }
+    for (uint32_t j = 0; j < size1; ++j) {
+      sum += vla1[j];
+    }
+  }
+  return sum;
+}