364da7e527
This patch attempts to scalarize the operand expressions of predicated instructions if they were conditionally executed in the original loop. After scalarization, the expressions will be sunk inside the blocks created for the predicated instructions. The transformation essentially performs un-if-conversion on the operands. The cost model has been updated to determine if scalarization is profitable. It compares the cost of a vectorized instruction, assuming it will be if-converted, to the cost of the scalarized instruction, assuming that the instructions corresponding to each vector lane will be sunk inside a predicated block, possibly avoiding execution. If it's more profitable to scalarize the entire expression tree feeding the predicated instruction, the expression will be scalarized; otherwise, it will be vectorized. We only consider the cost of the entire expression to accurately estimate the cost of the required insertelement and extractelement instructions. Differential Revision: https://reviews.llvm.org/D26083 llvm-svn: 288909
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 -enable-cond-stores-vec -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: Found an estimated cost of 5 for VF 2 For instruction: %tmp4 = udiv i32 %tmp2, %tmp3
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; CHECK: Scalarizing and predicating: %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: Found an estimated cost of 3 for VF 2 For instruction: store i32 %tmp2, i32* %tmp0, align 4
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; CHECK: Scalarizing and predicating: 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: 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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; 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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;
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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: 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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; 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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;
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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: 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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; 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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;
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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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