forked from OSchip/llvm-project
92 lines
3.4 KiB
LLVM
92 lines
3.4 KiB
LLVM
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; RUN: llc -mtriple=x86_64-pc-linux -x86-cmov-converter=true -verify-machineinstrs < %s | FileCheck %s
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; This test checks that x86-cmov-converter optimization does not transform CMOV
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;; instruction when the gain (in cycles) of converting to branch is less than
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;; a fix threshold (measured for "-x86-cmov-converter-threshold=4").
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;;
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;; Test was created using the following command line:
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;; > clang -S -O2 -m64 -fno-vectorize -fno-unroll-loops -emit-llvm foo.c -o -
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;; Where foo.c is:
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;int bar(int *a, int *b, int n) {
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;; int sum = 0;
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;; for (int i = 0; i < n; ++i) {
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;; int x = a[i] * a[i+1] * a[i+2];
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;; int y = b[i] * b[i+1];
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;; sum += y > x ? x : 0;
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;; }
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;; return sum;
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;;}
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Adding a test to the above function shows code with CMOV is 25% faster than
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;; the code with branch.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;#define N 10000
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;;int A[N];
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;;int B[N];
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;;
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;;
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;;
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;;int main () {
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;; for (int i=0; i< N; ++i) {
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;; A[i] = i%4;
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;; B[i] = i%5;
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;; }
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;; int sum = 0;
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;; for (int i=0; i< N*10; ++i)
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;; sum += bar(A, B, N);
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;; return sum;
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;;}
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; CHECK-NOT: jg
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; CHECK: cmovle
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define i32 @bar(i32* nocapture readonly %a, i32* nocapture readonly %b, i32 %n) #0 {
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entry:
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%cmp30 = icmp sgt i32 %n, 0
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br i1 %cmp30, label %for.body.preheader, label %for.cond.cleanup
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for.body.preheader: ; preds = %entry
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%.pre = load i32, i32* %a, align 4
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%arrayidx2.phi.trans.insert = getelementptr inbounds i32, i32* %a, i64 1
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%.pre34 = load i32, i32* %arrayidx2.phi.trans.insert, align 4
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%.pre35 = load i32, i32* %b, align 4
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%wide.trip.count = zext i32 %n to i64
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br label %for.body
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for.cond.cleanup: ; preds = %for.body, %entry
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%sum.0.lcssa = phi i32 [ 0, %entry ], [ %add14, %for.body ]
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ret i32 %sum.0.lcssa
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for.body: ; preds = %for.body, %for.body.preheader
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%0 = phi i32 [ %.pre35, %for.body.preheader ], [ %5, %for.body ]
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%1 = phi i32 [ %.pre34, %for.body.preheader ], [ %4, %for.body ]
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%2 = phi i32 [ %.pre, %for.body.preheader ], [ %1, %for.body ]
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%indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %for.body ]
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%sum.032 = phi i32 [ 0, %for.body.preheader ], [ %add14, %for.body ]
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%mul = mul nsw i32 %1, %2
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%3 = add nuw nsw i64 %indvars.iv, 2
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%arrayidx5 = getelementptr inbounds i32, i32* %a, i64 %3
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%4 = load i32, i32* %arrayidx5, align 4
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%mul6 = mul nsw i32 %mul, %4
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%arrayidx11 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv.next
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%5 = load i32, i32* %arrayidx11, align 4
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%mul12 = mul nsw i32 %5, %0
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%cmp13 = icmp sgt i32 %mul12, %mul6
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%cond = select i1 %cmp13, i32 %mul6, i32 0
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%add14 = add nsw i32 %cond, %sum.032
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%exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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}
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attributes #0 = {"target-cpu"="skylake"}
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!llvm.module.flags = !{!0, !1}
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!llvm.ident = !{!2}
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!0 = !{i32 1, !"wchar_size", i32 2}
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!1 = !{i32 7, !"PIC Level", i32 2}
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!2 = !{!"clang version 5.0.0 (trunk)"}
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