44475363e8
This patch really contains two pieces:
Teach SCEV how to fold a phi in the header of a loop to the value on the backedge when a) the backedge is known to execute at least once, and b) the value is safe to use globally within the scope dominated by the original phi.
Teach IndVarSimplify's rewriteLoopExitValues to allow loop invariant expressions which already exist (and thus don't need new computation inserted) even in loops where we can't optimize away other uses.
Differential Revision: https://reviews.llvm.org/D63224
llvm-svn: 363619
247 lines
6.7 KiB
LLVM
247 lines
6.7 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -indvars -loop-deletion -simplifycfg -S | FileCheck %s
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; Test that we can evaluate the exit values of various expression types. Since
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; these loops all have predictable exit values we can replace the use outside
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; of the loop with a closed-form computation.
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define i32 @polynomial_constant() {
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; <label>:0
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; CHECK-LABEL: @polynomial_constant(
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; CHECK-NEXT: Out:
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; CHECK-NEXT: ret i32 500500
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;
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br label %Loop
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Loop: ; preds = %Loop, %0
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%A1 = phi i32 [ 0, %0 ], [ %A2, %Loop ] ; <i32> [#uses=3]
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%B1 = phi i32 [ 0, %0 ], [ %B2, %Loop ] ; <i32> [#uses=1]
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%A2 = add i32 %A1, 1 ; <i32> [#uses=1]
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%B2 = add i32 %B1, %A1 ; <i32> [#uses=2]
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%C = icmp eq i32 %A1, 1000 ; <i1> [#uses=1]
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br i1 %C, label %Out, label %Loop
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Out: ; preds = %Loop
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ret i32 %B2
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}
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define i32 @NSquare(i32 %N) {
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; <label>:0
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; CHECK-LABEL: @NSquare(
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; CHECK-NEXT: Out:
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; CHECK-NEXT: [[Y:%.*]] = mul i32 [[N:%.*]], [[N]]
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; CHECK-NEXT: ret i32 [[Y]]
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;
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br label %Loop
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Loop: ; preds = %Loop, %0
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%X = phi i32 [ 0, %0 ], [ %X2, %Loop ] ; <i32> [#uses=4]
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%X2 = add i32 %X, 1 ; <i32> [#uses=1]
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%c = icmp eq i32 %X, %N ; <i1> [#uses=1]
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br i1 %c, label %Out, label %Loop
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Out: ; preds = %Loop
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%Y = mul i32 %X, %X ; <i32> [#uses=1]
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ret i32 %Y
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}
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define i32 @NSquareOver2(i32 %N) {
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; <label>:0
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; CHECK-LABEL: @NSquareOver2(
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; CHECK-NEXT: Out:
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; CHECK-NEXT: [[TMP0:%.*]] = zext i32 [[N:%.*]] to i33
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; CHECK-NEXT: [[TMP1:%.*]] = add i32 [[N]], -1
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; CHECK-NEXT: [[TMP2:%.*]] = zext i32 [[TMP1]] to i33
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; CHECK-NEXT: [[TMP3:%.*]] = mul i33 [[TMP0]], [[TMP2]]
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; CHECK-NEXT: [[TMP4:%.*]] = lshr i33 [[TMP3]], 1
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; CHECK-NEXT: [[TMP5:%.*]] = trunc i33 [[TMP4]] to i32
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; CHECK-NEXT: [[TMP6:%.*]] = add i32 [[N]], [[TMP5]]
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; CHECK-NEXT: [[TMP7:%.*]] = add i32 [[TMP6]], 15
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; CHECK-NEXT: ret i32 [[TMP7]]
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;
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br label %Loop
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Loop: ; preds = %Loop, %0
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%X = phi i32 [ 0, %0 ], [ %X2, %Loop ] ; <i32> [#uses=3]
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%Y = phi i32 [ 15, %0 ], [ %Y2, %Loop ] ; <i32> [#uses=1]
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%Y2 = add i32 %Y, %X ; <i32> [#uses=2]
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%X2 = add i32 %X, 1 ; <i32> [#uses=1]
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%c = icmp eq i32 %X, %N ; <i1> [#uses=1]
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br i1 %c, label %Out, label %Loop
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Out: ; preds = %Loop
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ret i32 %Y2
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}
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define i32 @strength_reduced() {
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; <label>:0
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; CHECK-LABEL: @strength_reduced(
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; CHECK-NEXT: Out:
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; CHECK-NEXT: ret i32 500500
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;
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br label %Loop
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Loop: ; preds = %Loop, %0
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%A1 = phi i32 [ 0, %0 ], [ %A2, %Loop ] ; <i32> [#uses=3]
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%B1 = phi i32 [ 0, %0 ], [ %B2, %Loop ] ; <i32> [#uses=1]
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%A2 = add i32 %A1, 1 ; <i32> [#uses=1]
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%B2 = add i32 %B1, %A1 ; <i32> [#uses=2]
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%C = icmp eq i32 %A1, 1000 ; <i1> [#uses=1]
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br i1 %C, label %Out, label %Loop
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Out: ; preds = %Loop
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ret i32 %B2
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}
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define i32 @chrec_equals() {
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; CHECK-LABEL: @chrec_equals(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: ret i32 101
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;
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entry:
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br label %no_exit
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no_exit: ; preds = %no_exit, %entry
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%i0 = phi i32 [ 0, %entry ], [ %i1, %no_exit ] ; <i32> [#uses=3]
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%ISq = mul i32 %i0, %i0 ; <i32> [#uses=1]
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%i1 = add i32 %i0, 1 ; <i32> [#uses=2]
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%tmp.1 = icmp ne i32 %ISq, 10000 ; <i1> [#uses=1]
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br i1 %tmp.1, label %no_exit, label %loopexit
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loopexit: ; preds = %no_exit
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ret i32 %i1
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}
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define i16 @cast_chrec_test() {
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; <label>:0
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; CHECK-LABEL: @cast_chrec_test(
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; CHECK-NEXT: Out:
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; CHECK-NEXT: ret i16 1000
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;
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br label %Loop
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Loop: ; preds = %Loop, %0
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%A1 = phi i32 [ 0, %0 ], [ %A2, %Loop ] ; <i32> [#uses=2]
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%B1 = trunc i32 %A1 to i16 ; <i16> [#uses=2]
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%A2 = add i32 %A1, 1 ; <i32> [#uses=1]
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%C = icmp eq i16 %B1, 1000 ; <i1> [#uses=1]
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br i1 %C, label %Out, label %Loop
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Out: ; preds = %Loop
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ret i16 %B1
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}
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define i32 @linear_div_fold() {
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; CHECK-LABEL: @linear_div_fold(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: ret i32 34
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;
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entry:
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br label %loop
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loop: ; preds = %loop, %entry
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%i = phi i32 [ 4, %entry ], [ %i.next, %loop ] ; <i32> [#uses=3]
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%i.next = add i32 %i, 8 ; <i32> [#uses=1]
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%RV = udiv i32 %i, 2 ; <i32> [#uses=1]
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%c = icmp ne i32 %i, 68 ; <i1> [#uses=1]
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br i1 %c, label %loop, label %loopexit
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loopexit: ; preds = %loop
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ret i32 %RV
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}
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define i32 @unroll_phi_select_constant_nonzero(i32 %arg1, i32 %arg2) {
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; CHECK-LABEL: @unroll_phi_select_constant_nonzero(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: ret i32 [[ARG2:%.*]]
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;
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entry:
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br label %loop
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loop:
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%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
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%selector = phi i32 [%arg1, %entry], [%arg2, %loop]
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%i.next = add nsw nuw i32 %i, 1
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%c = icmp ult i32 %i, 4
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br i1 %c, label %loop, label %loopexit
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loopexit:
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ret i32 %selector
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}
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declare i32 @f()
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; After LCSSA formation, there's no LCSSA phi for %f since it isn't directly
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; used outside the loop, and thus we can't directly replace %selector w/ %f.
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define i32 @neg_unroll_phi_select_constant_nonzero(i32 %arg) {
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; CHECK-LABEL: @neg_unroll_phi_select_constant_nonzero(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[I_NEXT:%.*]], [[LOOP]] ]
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; CHECK-NEXT: [[SELECTOR:%.*]] = phi i32 [ [[ARG:%.*]], [[ENTRY]] ], [ [[F:%.*]], [[LOOP]] ]
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; CHECK-NEXT: [[F]] = call i32 @f()
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; CHECK-NEXT: [[I_NEXT]] = add nuw nsw i32 [[I]], 1
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; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[I]], 4
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; CHECK-NEXT: br i1 [[C]], label [[LOOP]], label [[LOOPEXIT:%.*]]
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; CHECK: loopexit:
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; CHECK-NEXT: [[SELECTOR_LCSSA:%.*]] = phi i32 [ [[SELECTOR]], [[LOOP]] ]
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; CHECK-NEXT: ret i32 [[SELECTOR_LCSSA]]
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;
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entry:
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br label %loop
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loop:
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%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
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%selector = phi i32 [%arg, %entry], [%f, %loop]
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%f = call i32 @f()
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%i.next = add nsw nuw i32 %i, 1
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%c = icmp ult i32 %i, 4
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br i1 %c, label %loop, label %loopexit
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loopexit:
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ret i32 %selector
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}
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define i32 @unroll_phi_select_constant_zero(i32 %arg1, i32 %arg2) {
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; CHECK-LABEL: @unroll_phi_select_constant_zero(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: ret i32 [[ARG1:%.*]]
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;
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entry:
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br label %loop
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loop:
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%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
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%selector = phi i32 [%arg1, %entry], [%arg2, %loop]
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%i.next = add i32 %i, 1
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%c = icmp ne i32 %i, 0
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br i1 %c, label %loop, label %loopexit
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loopexit:
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ret i32 %selector
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}
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define i32 @unroll_phi_select(i32 %arg1, i32 %arg2, i16 %len) {
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; CHECK-LABEL: @unroll_phi_select(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[LENGTH:%.*]] = zext i16 [[LEN:%.*]] to i32
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; CHECK-NEXT: ret i32 [[ARG2:%.*]]
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;
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entry:
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%length = zext i16 %len to i32
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br label %loop
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loop:
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%i = phi i32 [ -1, %entry ], [ %i.next, %loop ]
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%selector = phi i32 [%arg1, %entry], [%arg2, %loop]
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%i.next = add nsw i32 %i, 1
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%c = icmp slt i32 %i, %length
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br i1 %c, label %loop, label %loopexit
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loopexit:
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ret i32 %selector
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}
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