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[SCCP] Use constant ranges for select, if cond is overdefined.
For selects with an unknown condition, we can approximate the result by merging the state of both options. This automatically takes care of the case where on operand is undef. Reviewers: davide, efriedma, mssimpso Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D71935
This commit is contained in:
Florian Hahn
parent
066b7f26f8
commit
3798c57e6c
@ -939,16 +939,10 @@ void SCCPSolver::visitSelectInst(SelectInst &I) {
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LatticeVal TVal = getValueState(I.getTrueValue());
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LatticeVal FVal = getValueState(I.getFalseValue());
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// select ?, C, C -> C.
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if (isConstant(TVal) && isConstant(FVal) &&
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getConstant(TVal) == getConstant(FVal))
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return (void)markConstant(&I, getConstant(FVal));
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if (TVal.isUnknownOrUndef()) // select ?, undef, X -> X.
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return (void)mergeInValue(&I, FVal);
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if (FVal.isUnknownOrUndef()) // select ?, X, undef -> X.
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return (void)mergeInValue(&I, TVal);
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markOverdefined(&I);
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bool Changed = ValueState[&I].mergeIn(TVal, DL);
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Changed |= ValueState[&I].mergeIn(FVal, DL);
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if (Changed)
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pushToWorkListMsg(ValueState[&I], &I);
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}
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// Handle Unary Operators.
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@ -35,3 +35,98 @@ bb12: ; preds = %bb8, %bb3, %bb
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}
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declare void @use(i32)
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define internal i1 @f1(i32 %x, i32 %y, i1 %cmp) {
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; CHECK-LABEL: define internal i1 @f1(i32 %x, i32 %y, i1 %cmp) {
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; CHECK-NEXT: %sel.1 = select i1 %cmp, i32 %x, i32 %y
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; CHECK-NEXT: %c.2 = icmp sgt i32 %sel.1, 100
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; CHECK-NEXT: %c.3 = icmp eq i32 %sel.1, 50
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; CHECK-NEXT: %res.1 = add i1 false, %c.2
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; CHECK-NEXT: %res.2 = add i1 %res.1, %c.3
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; CHECK-NEXT: %res.3 = add i1 %res.2, false
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; CHECK-NEXT: ret i1 %res.3
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;
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%sel.1 = select i1 %cmp, i32 %x, i32 %y
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%c.1 = icmp sgt i32 %sel.1, 300
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%c.2 = icmp sgt i32 %sel.1, 100
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%c.3 = icmp eq i32 %sel.1, 50
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%c.4 = icmp slt i32 %sel.1, 9
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%res.1 = add i1 %c.1, %c.2
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%res.2 = add i1 %res.1, %c.3
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%res.3 = add i1 %res.2, %c.4
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ret i1 %res.3
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}
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define i1 @caller1(i1 %cmp) {
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; CHECK-LABEL: define i1 @caller1(i1 %cmp) {
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; CHECK-NEXT: %call.1 = tail call i1 @f1(i32 10, i32 100, i1 %cmp)
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; CHECK-NEXT: %call.2 = tail call i1 @f1(i32 20, i32 200, i1 %cmp)
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; CHECK-NEXT: %res = and i1 %call.1, %call.2
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; CHECK-NEXT: ret i1 %res
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;
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%call.1 = tail call i1 @f1(i32 10, i32 100, i1 %cmp)
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%call.2 = tail call i1 @f1(i32 20, i32 200, i1 %cmp)
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%res = and i1 %call.1, %call.2
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ret i1 %res
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}
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define i1 @f2(i32 %x, i32 %y, i1 %cmp) {
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; CHECK-LABEL: define i1 @f2(i32 %x, i32 %y, i1 %cmp) {
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; CHECK-NEXT: %sel.1 = select i1 %cmp, i32 %x, i32 %y
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; CHECK-NEXT: %c.1 = icmp sgt i32 %sel.1, 300
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; CHECK-NEXT: %c.2 = icmp sgt i32 %sel.1, 100
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; CHECK-NEXT: %c.3 = icmp eq i32 %sel.1, 50
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; CHECK-NEXT: %c.4 = icmp slt i32 %sel.1, 9
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; CHECK-NEXT: %res.1 = add i1 %c.1, %c.2
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; CHECK-NEXT: %res.2 = add i1 %res.1, %c.3
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; CHECK-NEXT: %res.3 = add i1 %res.2, %c.4
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; CHECK-NEXT: ret i1 %res.3
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;
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%sel.1 = select i1 %cmp, i32 %x, i32 %y
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%c.1 = icmp sgt i32 %sel.1, 300
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%c.2 = icmp sgt i32 %sel.1, 100
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%c.3 = icmp eq i32 %sel.1, 50
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%c.4 = icmp slt i32 %sel.1, 9
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%res.1 = add i1 %c.1, %c.2
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%res.2 = add i1 %res.1, %c.3
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%res.3 = add i1 %res.2, %c.4
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ret i1 %res.3
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}
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define i1 @caller2(i32 %y, i1 %cmp) {
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; CHECK-LABEL: define i1 @caller2(i32 %y, i1 %cmp) {
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; CHECK-NEXT: %call.1 = tail call i1 @f2(i32 10, i32 %y, i1 %cmp)
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; CHECK-NEXT: %call.2 = tail call i1 @f2(i32 20, i32 %y, i1 %cmp)
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; CHECK-NEXT: %res = and i1 %call.1, %call.2
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; CHECK-NEXT: ret i1 %res
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;
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%call.1 = tail call i1 @f2(i32 10, i32 %y, i1 %cmp)
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%call.2 = tail call i1 @f2(i32 20, i32 %y, i1 %cmp)
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%res = and i1 %call.1, %call.2
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ret i1 %res
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}
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@GV = external global i32
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define i32 @f3_constantexpr_cond(i32 %x, i32 %y) {
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; CHECK-LABEL: define i32 @f3_constantexpr_cond(i32 %x, i32 %y)
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; CHECK-NEXT: %sel.1 = select i1 icmp eq (i32* bitcast (i32 (i32, i32)* @f3_constantexpr_cond to i32*), i32* @GV), i32 %x, i32 %y
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; CHECK-NEXT: ret i32 %sel.1
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;
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%sel.1 = select i1 icmp eq (i32* bitcast (i32 (i32, i32)* @f3_constantexpr_cond to i32*), i32* @GV), i32 %x, i32 %y
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ret i32 %sel.1
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}
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define i32 @caller3(i32 %y) {
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; CHECK-LABEL: define i32 @caller3(i32 %y) {
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; CHECK-NEXT: %call.1 = tail call i32 @f3_constantexpr_cond(i32 10, i32 %y)
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; CHECK-NEXT: %call.2 = tail call i32 @f3_constantexpr_cond(i32 20, i32 %y)
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; CHECK-NEXT: %res = and i32 %call.1, %call.2
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; CHECK-NEXT: ret i32 %res
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;
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%call.1 = tail call i32 @f3_constantexpr_cond(i32 10, i32 %y)
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%call.2 = tail call i32 @f3_constantexpr_cond(i32 20, i32 %y)
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%res = and i32 %call.1, %call.2
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ret i32 %res
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}
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@ -1,12 +1,40 @@
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; RUN: opt < %s -sccp -S | not grep select
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; RUN: opt < %s -sccp -S | FileCheck %s
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define i32 @test1(i1 %C) {
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; CHECK-LABEL: define i32 @test1(
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; CHECK-NEXT: ret i32 0
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;
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%X = select i1 %C, i32 0, i32 0 ; <i32> [#uses=1]
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ret i32 %X
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}
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define i32 @test2(i1 %C) {
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; CHECK-LABEL: define i32 @test2(
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; CHECK-NEXT: ret i32 0
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;
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%X = select i1 %C, i32 0, i32 undef ; <i32> [#uses=1]
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ret i32 %X
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}
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define i1 @f2(i32 %x, i1 %cmp) {
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; CHECK-LABEL: define i1 @f2(i32 %x, i1 %cmp) {
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; CHECK-NEXT: %sel.1 = select i1 %cmp, i32 %x, i32 10
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; CHECK-NEXT: %c.1 = icmp sgt i32 %sel.1, 300
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; CHECK-NEXT: %c.2 = icmp sgt i32 %sel.1, 100
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; CHECK-NEXT: %c.3 = icmp eq i32 %sel.1, 50
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; CHECK-NEXT: %c.4 = icmp slt i32 %sel.1, 9
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; CHECK-NEXT: %res.1 = add i1 %c.1, %c.2
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; CHECK-NEXT: %res.2 = add i1 %res.1, %c.3
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; CHECK-NEXT: %res.3 = add i1 %res.2, %c.4
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; CHECK-NEXT: ret i1 %res.3
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;
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%sel.1 = select i1 %cmp, i32 %x, i32 10
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%c.1 = icmp sgt i32 %sel.1, 300
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%c.2 = icmp sgt i32 %sel.1, 100
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%c.3 = icmp eq i32 %sel.1, 50
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%c.4 = icmp slt i32 %sel.1, 9
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%res.1 = add i1 %c.1, %c.2
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%res.2 = add i1 %res.1, %c.3
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%res.3 = add i1 %res.2, %c.4
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ret i1 %res.3
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}
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