// If LHS or RHS is an addrec, check to see if the condition is true in
// every iteration of the loop.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
- if (isLoopEntryGuardedByCond(
- AR->getLoop(), Pred, AR->getStart(), RHS) &&
- isLoopBackedgeGuardedByCond(
- AR->getLoop(), Pred, AR->getPostIncExpr(*this), RHS))
- return true;
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS))
- if (isLoopEntryGuardedByCond(
- AR->getLoop(), Pred, LHS, AR->getStart()) &&
- isLoopBackedgeGuardedByCond(
- AR->getLoop(), Pred, LHS, AR->getPostIncExpr(*this)))
- return true;
+ // If LHS and RHS are both addrec, both conditions must be true in
+ // every iteration of the loop.
+ const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
+ const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
+ bool LeftGuarded = false;
+ bool RightGuarded = false;
+ if (LAR) {
+ const Loop *L = LAR->getLoop();
+ if (isLoopEntryGuardedByCond(L, Pred, LAR->getStart(), RHS) &&
+ isLoopBackedgeGuardedByCond(L, Pred, LAR->getPostIncExpr(*this), RHS)) {
+ if (!RAR) return true;
+ LeftGuarded = true;
+ }
+ }
+ if (RAR) {
+ const Loop *L = RAR->getLoop();
+ if (isLoopEntryGuardedByCond(L, Pred, LHS, RAR->getStart()) &&
+ isLoopBackedgeGuardedByCond(L, Pred, LHS, RAR->getPostIncExpr(*this))) {
+ if (!LAR) return true;
+ RightGuarded = true;
+ }
+ }
+ if (LeftGuarded && RightGuarded)
+ return true;
// Otherwise see what can be done with known constant ranges.
return isKnownPredicateWithRanges(Pred, LHS, RHS);
--- /dev/null
+; RUN: opt -indvars -S < %s | FileCheck %s
+
+; indvars should transform the phi node pair from the for-loop
+; CHECK-LABEL: @main(
+; CHECK: ret = phi i32 [ 0, %entry ], [ 0, {{.*}} ]
+
+@c = common global i32 0, align 4
+
+define i32 @main() #0 {
+entry:
+ %0 = load i32* @c, align 4
+ %tobool = icmp eq i32 %0, 0
+ br i1 %tobool, label %for.body, label %exit
+
+for.body:
+ %inc2 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+ %sub = add i32 %inc2, -1
+ %cmp1 = icmp uge i32 %sub, %inc2
+ %conv = zext i1 %cmp1 to i32
+ br label %for.inc
+
+for.inc:
+ %inc = add nsw i32 %inc2, 1
+ %cmp = icmp slt i32 %inc, 5
+ br i1 %cmp, label %for.body, label %exit
+
+exit:
+ %ret = phi i32 [ 0, %entry ], [ %conv, %for.inc ]
+ ret i32 %ret
+}