From 1461ad6fccd3c7317f25158c44122007f106436e Mon Sep 17 00:00:00 2001
From: bbbradsmith <bbbradsmith@users.noreply.github.com>
Date: Thu, 16 May 2019 15:56:09 -0400
Subject: [PATCH] unit test to catch regression of bug #895

---
 test/val/bug895.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 test/val/bug895.c

diff --git a/test/val/bug895.c b/test/val/bug895.c
new file mode 100644
index 000000000..dc9f1cb42
--- /dev/null
+++ b/test/val/bug895.c
@@ -0,0 +1,81 @@
+/** This test is related to GitHub issue 895
+ ** https://github.com/cc65/cc65/issues/895
+ **
+ ** The OptCmp8 optimization attempts to eliminate an unnecessary
+ ** comparison and branch when the operands of the comparison are
+ ** known to be constant at compile time.
+ **
+ ** For 8-bit types it worked well, but for larger types it failed
+ ** to generate correct code. The bug manifest as a branch on an
+ ** uninitialized carry flag.
+ **
+ ** This does four tests for each type tested:
+ **   1: < with carry clear
+ **   2: >= with carry clear
+ **   3: < with carry set
+ **   4: >= with carry set
+ */
+
+#include "unittest.h"
+
+signed char   sca, scb;
+signed int    sia, sib;
+signed long   sla, slb;
+
+unsigned char uca, ucb;
+unsigned int  uia, uib;
+unsigned long ula, ulb;
+
+#define OPTCMP8TEST(vara,varb,startb,starta,cmpa,setb,printterm,typename,name) \
+    void name ## 1(void) { \
+    varb = startb; \
+    asm("clc"); \
+    vara = starta; \
+    if (vara < cmpa) varb = setb; \
+    ASSERT_AreEqual(startb, varb, printterm, "Incorrect optimization of " typename " comparison (1: < clc)."); \
+    } \
+    void name ## 2(void) { \
+    varb = startb; \
+    asm("sec"); \
+    vara = starta; \
+    if (vara < cmpa) varb = setb; \
+    ASSERT_AreEqual(startb, varb, printterm, "Incorrect optimization of " typename " comparison (2: < sec)."); \
+    } \
+    void name ## 3(void) { \
+    varb = startb; \
+    asm("clc"); \
+    vara = starta; \
+    if (vara >= cmpa) varb = setb; \
+    ASSERT_AreEqual(setb, varb, printterm, "Incorrect optimization of " typename " comparison (3: >= clc)."); \
+    } \
+    void name ## 4(void) { \
+    varb = startb; \
+    asm("sec"); \
+    vara = starta; \
+    if (vara >= cmpa) varb = setb; \
+    ASSERT_AreEqual(setb, varb, printterm, "Incorrect optimization of " typename " comparison (4: >= sec)."); \
+    }
+
+#define RUNOPTCMP8TEST(name) \
+    name ## 1(); \
+    name ## 2(); \
+    name ## 3(); \
+    name ## 4();
+
+OPTCMP8TEST(sca,scb,-20,100,50,5,"%d","signed char",signed_char);
+OPTCMP8TEST(uca,ucb,20,100,50,5,"%u","unsigned char",unsigned_char);
+OPTCMP8TEST(sia,sib,-2000,1000,500,50,"%d","signed int",signed_int);
+OPTCMP8TEST(uia,uib,2000,1000,500,50,"%u","unsigned int",unsigned_int);
+OPTCMP8TEST(sla,slb,-200000L,100000L,50000L,5000L,"%d","signed long",signed_long);
+OPTCMP8TEST(ula,ulb,200000UL,100000UL,50000UL,5000UL,"%u","unsigned long",unsigned_long);
+
+TEST
+{
+    RUNOPTCMP8TEST(signed_char);
+    RUNOPTCMP8TEST(unsigned_char);
+    RUNOPTCMP8TEST(signed_int);
+    RUNOPTCMP8TEST(unsigned_int);
+    RUNOPTCMP8TEST(signed_long);
+    RUNOPTCMP8TEST(unsigned_long);
+}
+ENDTEST