According to "strict weak ordering" rules, isInstPrecede function needs to return false value if compared values are equal, to be used as a comparator in std functions

aratajew · gfxbot · commit ea7883506f8a · 2019-04-04T15:20:43.000-07:00
Change-Id: I0e91da3c0b20e4c24324eaa211e3d80f7ab26025
diff --git a/IGC/Compiler/CISACodeGen/CodeSinking.cpp b/IGC/Compiler/CISACodeGen/CodeSinking.cpp
@@ -976,7 +976,7 @@ bool CodeSinking::hoistCongruentPhi(PHINode* phi)
             if (apply)
             {
                 auto compareFunc = [](const InstPair& a, const InstPair& b) {
-                    return (a.first == b.first) ? false : isInstPrecede(a.first, b.first);
+                    return isInstPrecede(a.first, b.first);
                 };
                 std::sort(instMap.begin(), instMap.end(), compareFunc);
 
diff --git a/IGC/Compiler/CISACodeGen/helper.h b/IGC/Compiler/CISACodeGen/helper.h
@@ -284,7 +284,7 @@ inline bool isInstPrecede(
     assert(inst->getParent() == pos->getParent());
     if (inst == pos)
     {
-        return true;
+        return false;
     }
 
     auto II = inst->getParent()->begin();

Original file line number	Diff line number	Diff line change
`@@ -976,7 +976,7 @@ bool CodeSinking::hoistCongruentPhi(PHINode* phi)`
`976`	`976`	`if (apply)`
`977`	`977`	`{`
`978`	`978`	`auto compareFunc = [](const InstPair& a, const InstPair& b) {`
`979`		`- return (a.first == b.first) ? false : isInstPrecede(a.first, b.first);`
	`979`	`+ return isInstPrecede(a.first, b.first);`
`980`	`980`	`};`
`981`	`981`	`std::sort(instMap.begin(), instMap.end(), compareFunc);`
`982`	`982`
Original file line number	Diff line number	Diff line change
`@@ -284,7 +284,7 @@ inline bool isInstPrecede(`
`284`	`284`	`assert(inst->getParent() == pos->getParent());`
`285`	`285`	`if (inst == pos)`
`286`	`286`	`{`
`287`		`- return true;`
	`287`	`+ return false;`
`288`	`288`	`}`
`289`	`289`
`290`	`290`	`auto II = inst->getParent()->begin();`