1 files changed, 151 insertions, 0 deletions
diff --git a/Python/instruction_sequence.c b/Python/instruction_sequence.c
new file mode 100644
index 0000000..597d2b7
--- /dev/null
+++ b/Python/instruction_sequence.c
@@ -0,0 +1,151 @@
+/*
+ * This file implements a data structure representing a sequence of
+ * instructions, which is used by different parts of the compilation
+ * pipeline.
+ */
+
+
+#include <stdbool.h>
+
+#include "Python.h"
+
+#include "pycore_compile.h" // _PyCompile_EnsureArrayLargeEnough
+#include "pycore_opcode_utils.h"
+#include "pycore_opcode_metadata.h" // OPCODE_HAS_ARG, etc
+
+typedef _PyInstruction instruction;
+typedef _PyInstructionSequence instr_sequence;
+typedef _Py_SourceLocation location;
+
+#define INITIAL_INSTR_SEQUENCE_SIZE 100
+#define INITIAL_INSTR_SEQUENCE_LABELS_MAP_SIZE 10
+
+#undef SUCCESS
+#undef ERROR
+#define SUCCESS 0
+#define ERROR -1
+
+#define RETURN_IF_ERROR(X)  \
+    if ((X) == -1) {        \
+        return ERROR;       \
+    }
+
+static int
+instr_sequence_next_inst(instr_sequence *seq) {
+    assert(seq->s_instrs != NULL || seq->s_used == 0);
+
+    RETURN_IF_ERROR(
+        _PyCompile_EnsureArrayLargeEnough(seq->s_used + 1,
+                                          (void**)&seq->s_instrs,
+                                          &seq->s_allocated,
+                                          INITIAL_INSTR_SEQUENCE_SIZE,
+                                          sizeof(instruction)));
+    assert(seq->s_allocated >= 0);
+    assert(seq->s_used < seq->s_allocated);
+    return seq->s_used++;
+}
+
+_PyJumpTargetLabel
+_PyInstructionSequence_NewLabel(instr_sequence *seq)
+{
+    _PyJumpTargetLabel lbl = {++seq->s_next_free_label};
+    return lbl;
+}
+
+int
+_PyInstructionSequence_UseLabel(instr_sequence *seq, int lbl)
+{
+    int old_size = seq->s_labelmap_size;
+    RETURN_IF_ERROR(
+        _PyCompile_EnsureArrayLargeEnough(lbl,
+                                          (void**)&seq->s_labelmap,
+                                           &seq->s_labelmap_size,
+                                           INITIAL_INSTR_SEQUENCE_LABELS_MAP_SIZE,
+                                           sizeof(int)));
+
+    for(int i = old_size; i < seq->s_labelmap_size; i++) {
+        seq->s_labelmap[i] = -111;  /* something weird, for debugging */
+    }
+    seq->s_labelmap[lbl] = seq->s_used; /* label refers to the next instruction */
+    return SUCCESS;
+}
+
+int
+_PyInstructionSequence_ApplyLabelMap(instr_sequence *instrs)
+{
+    if (instrs->s_labelmap == NULL) {
+        /* Already applied - nothing to do */
+        return SUCCESS;
+    }
+    /* Replace labels by offsets in the code */
+    for (int i=0; i < instrs->s_used; i++) {
+        instruction *instr = &instrs->s_instrs[i];
+        if (HAS_TARGET(instr->i_opcode)) {
+            assert(instr->i_oparg < instrs->s_labelmap_size);
+            instr->i_oparg = instrs->s_labelmap[instr->i_oparg];
+        }
+        _PyExceptHandlerInfo *hi = &instr->i_except_handler_info;
+        if (hi->h_label >= 0) {
+            assert(hi->h_label < instrs->s_labelmap_size);
+            hi->h_label = instrs->s_labelmap[hi->h_label];
+        }
+    }
+    /* Clear label map so it's never used again */
+    PyMem_Free(instrs->s_labelmap);
+    instrs->s_labelmap = NULL;
+    instrs->s_labelmap_size = 0;
+    return SUCCESS;
+}
+
+#define MAX_OPCODE 511
+
+int
+_PyInstructionSequence_Addop(instr_sequence *seq, int opcode, int oparg,
+                             location loc)
+{
+    assert(0 <= opcode && opcode <= MAX_OPCODE);
+    assert(IS_WITHIN_OPCODE_RANGE(opcode));
+    assert(OPCODE_HAS_ARG(opcode) || HAS_TARGET(opcode) || oparg == 0);
+    assert(0 <= oparg && oparg < (1 << 30));
+
+    int idx = instr_sequence_next_inst(seq);
+    RETURN_IF_ERROR(idx);
+    instruction *ci = &seq->s_instrs[idx];
+    ci->i_opcode = opcode;
+    ci->i_oparg = oparg;
+    ci->i_loc = loc;
+    return SUCCESS;
+}
+
+int
+_PyInstructionSequence_InsertInstruction(instr_sequence *seq, int pos,
+                                         int opcode, int oparg, location loc)
+{
+    assert(pos >= 0 && pos <= seq->s_used);
+    int last_idx = instr_sequence_next_inst(seq);
+    RETURN_IF_ERROR(last_idx);
+    for (int i=last_idx-1; i >= pos; i--) {
+        seq->s_instrs[i+1] = seq->s_instrs[i];
+    }
+    instruction *ci = &seq->s_instrs[pos];
+    ci->i_opcode = opcode;
+    ci->i_oparg = oparg;
+    ci->i_loc = loc;
+
+    /* fix the labels map */
+    for(int lbl=0; lbl < seq->s_labelmap_size; lbl++) {
+        if (seq->s_labelmap[lbl] >= pos) {
+            seq->s_labelmap[lbl]++;
+        }
+    }
+    return SUCCESS;
+}
+
+void
+PyInstructionSequence_Fini(instr_sequence *seq) {
+    PyMem_Free(seq->s_labelmap);
+    seq->s_labelmap = NULL;
+
+    PyMem_Free(seq->s_instrs);
+    seq->s_instrs = NULL;
+}