From aaac9284b407d236981cbe9be9b167c67cc905ba Mon Sep 17 00:00:00 2001
From: Jack Palevich <jackpal@google.com>
Date: Fri, 31 Jul 2009 14:34:34 -0700
Subject: Implement pre-increment / pre-decrement

---
 libacc/acc.cpp          | 62 ++++++++++++++++++++++++++++---------------------
 libacc/tests/data/inc.c |  4 ++++
 libacc/tests/test.py    |  4 ++++
 3 files changed, 43 insertions(+), 27 deletions(-)

diff --git a/libacc/acc.cpp b/libacc/acc.cpp
index da703a70..327d3da7 100644
--- a/libacc/acc.cpp
+++ b/libacc/acc.cpp
@@ -3859,7 +3859,12 @@ class Compiler : public ErrorSink {
                 } else {
                     pGen->genUnaryOp(a);
                 }
-            } else if (t == '(') {
+            } else if (c == 11) {
+                // pre increment / pre decrement
+                unary();
+                doIncDec(a == OP_INCREMENT, 0);
+            }
+            else if (t == '(') {
                 // It's either a cast or an expression
                 Type* pCast = acceptCastTypeDeclaration();
                 if (pCast) {
@@ -3926,35 +3931,11 @@ class Compiler : public ErrorSink {
                         }
                     }
                     // load a variable
+                    pGen->leaR0(n, createPtrType(pVI->pType), ET_LVALUE);
                     if (tokl == 11) {
                         // post inc / post dec
-                        pGen->leaR0(n, createPtrType(pVI->pType), ET_LVALUE);
-
-                        pGen->pushR0();
-                        pGen->loadR0FromR0();
-                        pGen->over();
-                        int lit = 1;
-                        if (tokc == OP_DECREMENT) {
-                            lit = -1;
-                        }
-                        switch (pVI->pType->tag) {
-                            case TY_INT:
-                            case TY_CHAR:
-                            case TY_POINTER:
-                                pGen->pushR0();
-                                pGen->li(lit);
-                                pGen->genOp(OP_PLUS);
-                                break;
-                            default:
-                                error("++/-- illegal for this type.");
-                                break;
-                        }
-
-                        pGen->storeR0ToTOS();
-                        pGen->popR0();
+                        doIncDec(tokc == OP_INCREMENT, true);
                         next();
-                    } else {
-                        pGen->leaR0(n, createPtrType(pVI->pType), ET_LVALUE);
                     }
                 }
             }
@@ -4029,6 +4010,33 @@ class Compiler : public ErrorSink {
         }
     }
 
+    void doIncDec(int isInc, int isPost) {
+        // R0 already has the lval
+        checkLVal();
+        int lit = isInc ? 1 : -1;
+        pGen->pushR0();
+        pGen->loadR0FromR0();
+        int tag = pGen->getR0Type()->tag;
+        if (!(tag == TY_INT || tag == TY_CHAR || tag == TY_POINTER)) {
+            error("++/-- illegal for this type. %d", tag);
+        }
+        if (isPost) {
+            pGen->over();
+            pGen->pushR0();
+            pGen->li(lit);
+            pGen->genOp(OP_PLUS);
+            pGen->storeR0ToTOS();
+            pGen->popR0();
+        } else {
+            pGen->pushR0();
+            pGen->li(lit);
+            pGen->genOp(OP_PLUS);
+            pGen->over();
+            pGen->storeR0ToTOS();
+            pGen->popR0();
+        }
+    }
+
     /* Recursive descent parser for binary operations.
      */
     void binaryOp(int level) {
diff --git a/libacc/tests/data/inc.c b/libacc/tests/data/inc.c
index eda3659a..14c09d18 100644
--- a/libacc/tests/data/inc.c
+++ b/libacc/tests/data/inc.c
@@ -6,5 +6,9 @@ int main() {
     printf("%d\n", a++);
     printf("%d\n", a--);
     printf("%d\n", a--);
+    printf("%d\n", ++a);
+    printf("%d\n", ++a);
+    printf("%d\n", --a);
+    printf("%d\n", --a);
     return a;
 }
diff --git a/libacc/tests/test.py b/libacc/tests/test.py
index 5f9a71e3..0249695f 100644
--- a/libacc/tests/test.py
+++ b/libacc/tests/test.py
@@ -293,6 +293,10 @@ result: 0""", """0.002 0.1 10""")
 1
 2
 1
+1
+2
+1
+0
 result: 0
 ""","""""")
 
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