1ccc49924a
D79164/2596da31740f changed getCFInstrCost to return 1 per default.
AArch64 did not have its own implementation, hence the throughput cost
of CFI instructions is overestimated. On most cores, most branches should
be predicated and essentially free throughput wise.
This restores a 9% performance regression on a SPEC2006 benchmark on
AArch64 with -O3 LTO & PGO.
This patch effectively restores pre 2596da3174 behavior for AArch64
and undoes the AArch64 test changes of the patch.
Reviewers: samparker, dmgreen, anemet
Reviewed By: samparker
Differential Revision: https://reviews.llvm.org/D82755
232 lines
7.5 KiB
LLVM
232 lines
7.5 KiB
LLVM
; REQUIRES: asserts
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; RUN: opt < %s -force-vector-width=2 -loop-vectorize -debug-only=loop-vectorize -disable-output 2>&1 | FileCheck %s
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target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
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target triple = "aarch64--linux-gnu"
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; Check predication-related cost calculations, including scalarization overhead
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; and block probability scaling. Note that the functionality being tested is
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; not specific to AArch64. We specify a target to get actual values for the
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; instruction costs.
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; CHECK-LABEL: predicated_udiv
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;
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; This test checks that we correctly compute the cost of the predicated udiv
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; instruction. If we assume the block probability is 50%, we compute the cost
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; as:
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;
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; Cost of udiv:
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; (udiv(2) + extractelement(6) + insertelement(3)) / 2 = 5
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;
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; CHECK: Scalarizing and predicating: %tmp4 = udiv i32 %tmp2, %tmp3
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; CHECK: Found an estimated cost of 5 for VF 2 For instruction: %tmp4 = udiv i32 %tmp2, %tmp3
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;
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define i32 @predicated_udiv(i32* %a, i32* %b, i1 %c, i64 %n) {
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entry:
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br label %for.body
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.inc ]
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%r = phi i32 [ 0, %entry ], [ %tmp6, %for.inc ]
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%tmp0 = getelementptr inbounds i32, i32* %a, i64 %i
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%tmp1 = getelementptr inbounds i32, i32* %b, i64 %i
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%tmp2 = load i32, i32* %tmp0, align 4
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%tmp3 = load i32, i32* %tmp1, align 4
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br i1 %c, label %if.then, label %for.inc
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if.then:
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%tmp4 = udiv i32 %tmp2, %tmp3
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br label %for.inc
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for.inc:
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%tmp5 = phi i32 [ %tmp3, %for.body ], [ %tmp4, %if.then]
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%tmp6 = add i32 %r, %tmp5
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%i.next = add nuw nsw i64 %i, 1
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%cond = icmp slt i64 %i.next, %n
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br i1 %cond, label %for.body, label %for.end
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for.end:
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%tmp7 = phi i32 [ %tmp6, %for.inc ]
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ret i32 %tmp7
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}
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; CHECK-LABEL: predicated_store
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;
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; This test checks that we correctly compute the cost of the predicated store
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; instruction. If we assume the block probability is 50%, we compute the cost
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; as:
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;
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; Cost of store:
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; (store(4) + extractelement(3)) / 2 = 3
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;
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; CHECK: Scalarizing and predicating: store i32 %tmp2, i32* %tmp0, align 4
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; CHECK: Found an estimated cost of 3 for VF 2 For instruction: store i32 %tmp2, i32* %tmp0, align 4
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;
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define void @predicated_store(i32* %a, i1 %c, i32 %x, i64 %n) {
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entry:
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br label %for.body
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.inc ]
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%tmp0 = getelementptr inbounds i32, i32* %a, i64 %i
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%tmp1 = load i32, i32* %tmp0, align 4
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%tmp2 = add nsw i32 %tmp1, %x
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br i1 %c, label %if.then, label %for.inc
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if.then:
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store i32 %tmp2, i32* %tmp0, align 4
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br label %for.inc
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for.inc:
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%i.next = add nuw nsw i64 %i, 1
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%cond = icmp slt i64 %i.next, %n
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br i1 %cond, label %for.body, label %for.end
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for.end:
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ret void
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}
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; CHECK-LABEL: predicated_udiv_scalarized_operand
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;
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; This test checks that we correctly compute the cost of the predicated udiv
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; instruction and the add instruction it uses. The add is scalarized and sunk
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; inside the predicated block. If we assume the block probability is 50%, we
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; compute the cost as:
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;
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; Cost of add:
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; (add(2) + extractelement(3)) / 2 = 2
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; Cost of udiv:
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; (udiv(2) + extractelement(3) + insertelement(3)) / 2 = 4
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;
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; CHECK: Scalarizing: %tmp3 = add nsw i32 %tmp2, %x
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; CHECK: Scalarizing and predicating: %tmp4 = udiv i32 %tmp2, %tmp3
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; CHECK: Found an estimated cost of 2 for VF 2 For instruction: %tmp3 = add nsw i32 %tmp2, %x
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; CHECK: Found an estimated cost of 4 for VF 2 For instruction: %tmp4 = udiv i32 %tmp2, %tmp3
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;
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define i32 @predicated_udiv_scalarized_operand(i32* %a, i1 %c, i32 %x, i64 %n) {
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entry:
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br label %for.body
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.inc ]
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%r = phi i32 [ 0, %entry ], [ %tmp6, %for.inc ]
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%tmp0 = getelementptr inbounds i32, i32* %a, i64 %i
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%tmp2 = load i32, i32* %tmp0, align 4
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br i1 %c, label %if.then, label %for.inc
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if.then:
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%tmp3 = add nsw i32 %tmp2, %x
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%tmp4 = udiv i32 %tmp2, %tmp3
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br label %for.inc
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for.inc:
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%tmp5 = phi i32 [ %tmp2, %for.body ], [ %tmp4, %if.then]
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%tmp6 = add i32 %r, %tmp5
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%i.next = add nuw nsw i64 %i, 1
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%cond = icmp slt i64 %i.next, %n
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br i1 %cond, label %for.body, label %for.end
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for.end:
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%tmp7 = phi i32 [ %tmp6, %for.inc ]
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ret i32 %tmp7
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}
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; CHECK-LABEL: predicated_store_scalarized_operand
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;
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; This test checks that we correctly compute the cost of the predicated store
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; instruction and the add instruction it uses. The add is scalarized and sunk
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; inside the predicated block. If we assume the block probability is 50%, we
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; compute the cost as:
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;
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; Cost of add:
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; (add(2) + extractelement(3)) / 2 = 2
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; Cost of store:
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; store(4) / 2 = 2
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;
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; CHECK: Scalarizing: %tmp2 = add nsw i32 %tmp1, %x
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; CHECK: Scalarizing and predicating: store i32 %tmp2, i32* %tmp0, align 4
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; CHECK: Found an estimated cost of 2 for VF 2 For instruction: %tmp2 = add nsw i32 %tmp1, %x
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; CHECK: Found an estimated cost of 2 for VF 2 For instruction: store i32 %tmp2, i32* %tmp0, align 4
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;
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define void @predicated_store_scalarized_operand(i32* %a, i1 %c, i32 %x, i64 %n) {
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entry:
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br label %for.body
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.inc ]
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%tmp0 = getelementptr inbounds i32, i32* %a, i64 %i
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%tmp1 = load i32, i32* %tmp0, align 4
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br i1 %c, label %if.then, label %for.inc
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if.then:
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%tmp2 = add nsw i32 %tmp1, %x
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store i32 %tmp2, i32* %tmp0, align 4
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br label %for.inc
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for.inc:
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%i.next = add nuw nsw i64 %i, 1
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%cond = icmp slt i64 %i.next, %n
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br i1 %cond, label %for.body, label %for.end
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for.end:
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ret void
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}
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; CHECK-LABEL: predication_multi_context
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;
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; This test checks that we correctly compute the cost of multiple predicated
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; instructions in the same block. The sdiv, udiv, and store must be scalarized
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; and predicated. The sub feeding the store is scalarized and sunk inside the
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; store's predicated block. However, the add feeding the sdiv and udiv cannot
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; be sunk and is not scalarized. If we assume the block probability is 50%, we
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; compute the cost as:
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;
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; Cost of add:
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; add(1) = 1
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; Cost of sdiv:
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; (sdiv(2) + extractelement(6) + insertelement(3)) / 2 = 5
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; Cost of udiv:
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; (udiv(2) + extractelement(6) + insertelement(3)) / 2 = 5
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; Cost of sub:
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; (sub(2) + extractelement(3)) / 2 = 2
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; Cost of store:
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; store(4) / 2 = 2
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;
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; CHECK-NOT: Scalarizing: %tmp2 = add i32 %tmp1, %x
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; CHECK: Scalarizing and predicating: %tmp3 = sdiv i32 %tmp1, %tmp2
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; CHECK: Scalarizing and predicating: %tmp4 = udiv i32 %tmp3, %tmp2
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; CHECK: Scalarizing: %tmp5 = sub i32 %tmp4, %x
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; CHECK: Scalarizing and predicating: store i32 %tmp5, i32* %tmp0, align 4
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; CHECK: Found an estimated cost of 1 for VF 2 For instruction: %tmp2 = add i32 %tmp1, %x
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; CHECK: Found an estimated cost of 5 for VF 2 For instruction: %tmp3 = sdiv i32 %tmp1, %tmp2
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; CHECK: Found an estimated cost of 5 for VF 2 For instruction: %tmp4 = udiv i32 %tmp3, %tmp2
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; CHECK: Found an estimated cost of 2 for VF 2 For instruction: %tmp5 = sub i32 %tmp4, %x
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; CHECK: Found an estimated cost of 2 for VF 2 For instruction: store i32 %tmp5, i32* %tmp0, align 4
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;
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define void @predication_multi_context(i32* %a, i1 %c, i32 %x, i64 %n) {
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entry:
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br label %for.body
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.inc ]
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%tmp0 = getelementptr inbounds i32, i32* %a, i64 %i
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%tmp1 = load i32, i32* %tmp0, align 4
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br i1 %c, label %if.then, label %for.inc
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if.then:
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%tmp2 = add i32 %tmp1, %x
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%tmp3 = sdiv i32 %tmp1, %tmp2
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%tmp4 = udiv i32 %tmp3, %tmp2
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%tmp5 = sub i32 %tmp4, %x
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store i32 %tmp5, i32* %tmp0, align 4
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br label %for.inc
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for.inc:
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%i.next = add nuw nsw i64 %i, 1
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%cond = icmp slt i64 %i.next, %n
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br i1 %cond, label %for.body, label %for.end
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for.end:
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ret void
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}
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