avoid infinite loop

ddcc · ddcc · commit 60a714e3154c · 2020-09-23T04:41:17.000-04:00
diff --git a/llvm-4.0.0.src/lib/Transforms/Instrumentation/LowFat.cpp b/llvm-4.0.0.src/lib/Transforms/Instrumentation/LowFat.cpp
@@ -540,7 +540,12 @@ static Bounds getPtrBounds(const TargetLibraryInfo *TLI, const DataLayout *DL,
     Bounds bounds = Bounds::nonFat();
     if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
     {
-        bounds = getPtrBounds(TLI, DL, GEP->getPointerOperand(), boundsInfo);
+        // JumpThreading or other optimizations may produce incorrect IR that
+        // has not yet been removed; e.g.
+        // %231 = getelementptr inbounds i8, i8* %231, i64 1
+        bounds = GEP != GEP->getPointerOperand() ?
+                 getPtrBounds(TLI, DL, GEP->getPointerOperand(), boundsInfo) :
+                 Bounds::nonFat();
         if (!bounds.isUnknown() && !bounds.isNonFat())
         {
             APInt offset(64, 0);

Original file line number	Diff line number	Diff line change
`@@ -540,7 +540,12 @@ static Bounds getPtrBounds(const TargetLibraryInfo TLI, const DataLayout DL,`
`540`	`540`	`Bounds bounds = Bounds::nonFat();`
`541`	`541`	`if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))`
`542`	`542`	`{`
`543`		`- bounds = getPtrBounds(TLI, DL, GEP->getPointerOperand(), boundsInfo);`
	`543`	`+ // JumpThreading or other optimizations may produce incorrect IR that`
	`544`	`+ // has not yet been removed; e.g.`
	`545`	`+ // %231 = getelementptr inbounds i8, i8* %231, i64 1`
	`546`	`+ bounds = GEP != GEP->getPointerOperand() ?`
	`547`	`+ getPtrBounds(TLI, DL, GEP->getPointerOperand(), boundsInfo) :`
	`548`	`+ Bounds::nonFat();`
`544`	`549`	`if (!bounds.isUnknown() && !bounds.isNonFat())`
`545`	`550`	`{`
`546`	`551`	`APInt offset(64, 0);`