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Simplify [su]max(MAX, n) to MAX. This comes up in loop tripcount
computations in loops with multiple exits. Adjust the testcase for PR4436 so that the relevant portion isn't optimized away. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74073 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1690,10 +1690,14 @@ ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV*> &Ops) {
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LHSC = cast<SCEVConstant>(Ops[0]);
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}
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// If we are left with a constant -inf, strip it off.
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// If we are left with a constant minimum-int, strip it off.
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if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
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Ops.erase(Ops.begin());
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--Idx;
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} else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
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// If we have an smax with a constant maximum-int, it will always be
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// maximum-int.
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return Ops[0];
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}
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}
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@ -1777,10 +1781,14 @@ ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV*> &Ops) {
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LHSC = cast<SCEVConstant>(Ops[0]);
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}
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// If we are left with a constant zero, strip it off.
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// If we are left with a constant minimum-int, strip it off.
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if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
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Ops.erase(Ops.begin());
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--Idx;
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} else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
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// If we have an umax with a constant maximum-int, it will always be
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// maximum-int.
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return Ops[0];
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}
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}
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@ -4,7 +4,7 @@
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
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target triple = "i386-pc-linux-gnu"
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define i8* @string_expandtabs() nounwind {
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define i8* @string_expandtabs(i32 %n, i8* %m) nounwind {
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entry:
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br i1 undef, label %bb33, label %bb1
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@ -22,11 +22,11 @@ bb19: ; preds = %bb30
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bb20: ; preds = %bb19
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%0 = load i32* undef, align 4 ; <i32> [#uses=1]
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%1 = sub i32 %0, undef ; <i32> [#uses=1]
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%1 = sub i32 %0, %n ; <i32> [#uses=1]
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br label %bb23
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bb21: ; preds = %bb23
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%2 = icmp ult i8* %q.0, undef ; <i1> [#uses=1]
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%2 = icmp ult i8* %q.0, %m ; <i1> [#uses=1]
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br i1 %2, label %bb22, label %overflow2
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bb22: ; preds = %bb21
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63
test/Transforms/IndVarSimplify/loop_evaluate8.ll
Normal file
63
test/Transforms/IndVarSimplify/loop_evaluate8.ll
Normal file
@ -0,0 +1,63 @@
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; RUN: llvm-as < %s | opt -indvars | llvm-dis | not grep select
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; This loop has backedge-taken-count zero. Indvars shouldn't expand any
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; instructions to compute a trip count.
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
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target triple = "i386-pc-linux-gnu"
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define i8* @string_expandtabs() nounwind {
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entry:
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br i1 undef, label %bb33, label %bb1
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bb1: ; preds = %entry
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br i1 undef, label %overflow1, label %bb15
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bb15: ; preds = %bb1
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br i1 undef, label %bb33, label %bb17
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bb17: ; preds = %bb15
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br label %bb30
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bb19: ; preds = %bb30
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br i1 undef, label %bb20, label %bb29
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bb20: ; preds = %bb19
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%0 = load i32* undef, align 4 ; <i32> [#uses=1]
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%1 = sub i32 %0, undef ; <i32> [#uses=1]
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br label %bb23
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bb21: ; preds = %bb23
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%2 = icmp ult i8* %q.0, undef ; <i1> [#uses=1]
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br i1 %2, label %bb22, label %overflow2
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bb22: ; preds = %bb21
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%3 = getelementptr i8* %q.0, i32 1 ; <i8*> [#uses=1]
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br label %bb23
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bb23: ; preds = %bb22, %bb20
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%i.2 = phi i32 [ %1, %bb20 ], [ %4, %bb22 ] ; <i32> [#uses=1]
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%q.0 = phi i8* [ undef, %bb20 ], [ %3, %bb22 ] ; <i8*> [#uses=3]
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%4 = add i32 %i.2, -1 ; <i32> [#uses=2]
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%5 = icmp eq i32 %4, -1 ; <i1> [#uses=1]
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br i1 %5, label %bb29, label %bb21
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bb29: ; preds = %bb23, %bb19
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%q.1 = phi i8* [ undef, %bb19 ], [ %q.0, %bb23 ] ; <i8*> [#uses=0]
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br label %bb30
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bb30: ; preds = %bb29, %bb17
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br i1 undef, label %bb19, label %bb33
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overflow2: ; preds = %bb21
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br i1 undef, label %bb32, label %overflow1
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bb32: ; preds = %overflow2
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br label %overflow1
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overflow1: ; preds = %bb32, %overflow2, %bb1
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ret i8* null
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bb33: ; preds = %bb30, %bb15, %entry
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ret i8* undef
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}
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