7227276d41
This canonicalization was suggested in D33172 as a way to make InstCombine behavior more uniform. We have this transform for icmp+br, so unless there's some reason that icmp+select should be treated differently, we should do the same thing here. The benefit comes from increasing the chances of creating identical instructions. This is shown in the tests in logical-select.ll (PR32791). InstCombine doesn't fold those directly, but EarlyCSE can simplify the identical cmps, and then InstCombine can fold the selects together. The possible regression for the tests in select.ll raises questions about poison/undef: http://lists.llvm.org/pipermail/llvm-dev/2017-May/113261.html ...but that transform is just as likely to be triggered by this canonicalization as it is to be missed, so we're just pointing out a commutation deficiency in the pattern matching: https://reviews.llvm.org/rL228409 Differential Revision: https://reviews.llvm.org/D34242 llvm-svn: 306435
171 lines
5.1 KiB
LLVM
171 lines
5.1 KiB
LLVM
; RUN: opt < %s -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -enable-if-conversion -dce -instcombine -S | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
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; This is the loop in this example:
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;
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;int function0(int *a, int *b, int start, int end) {
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;
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; for (int i=start; i<end; ++i) {
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; unsigned k = a[i];
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;
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; if (a[i] > b[i]) <------ notice the IF inside the loop.
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; k = k * 5 + 3;
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;
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; a[i] = k; <---- K is a phi node that becomes vector-select.
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; }
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;}
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;CHECK-LABEL: @function0(
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;CHECK: load <4 x i32>
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;CHECK: icmp sgt <4 x i32>
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;CHECK: mul <4 x i32>
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;CHECK: add <4 x i32>
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;CHECK: select <4 x i1>
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;CHECK: ret i32
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define i32 @function0(i32* nocapture %a, i32* nocapture %b, i32 %start, i32 %end) nounwind uwtable ssp {
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entry:
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%cmp16 = icmp slt i32 %start, %end
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br i1 %cmp16, label %for.body.lr.ph, label %for.end
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for.body.lr.ph:
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%0 = sext i32 %start to i64
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br label %for.body
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for.body:
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%indvars.iv = phi i64 [ %0, %for.body.lr.ph ], [ %indvars.iv.next, %if.end ]
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%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
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%1 = load i32, i32* %arrayidx, align 4
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%arrayidx4 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
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%2 = load i32, i32* %arrayidx4, align 4
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%cmp5 = icmp sgt i32 %1, %2
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br i1 %cmp5, label %if.then, label %if.end
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if.then:
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%mul = mul i32 %1, 5
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%add = add i32 %mul, 3
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br label %if.end
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if.end:
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%k.0 = phi i32 [ %add, %if.then ], [ %1, %for.body ]
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store i32 %k.0, i32* %arrayidx, align 4
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%indvars.iv.next = add i64 %indvars.iv, 1
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%3 = trunc i64 %indvars.iv.next to i32
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%cmp = icmp slt i32 %3, %end
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br i1 %cmp, label %for.body, label %for.end
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for.end:
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ret i32 undef
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}
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; int func(int *A, int n) {
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; unsigned sum = 0;
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; for (int i = 0; i < n; ++i)
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; if (A[i] > 30)
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; sum += A[i] + 2;
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;
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; return sum;
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; }
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;CHECK-LABEL: @reduction_func(
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;CHECK: load <4 x i32>
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;CHECK: icmp slt <4 x i32>
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;CHECK: add <4 x i32>
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;CHECK: select <4 x i1>
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;CHECK: ret i32
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define i32 @reduction_func(i32* nocapture %A, i32 %n) nounwind uwtable readonly ssp {
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entry:
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%cmp10 = icmp sgt i32 %n, 0
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br i1 %cmp10, label %for.body, label %for.end
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for.body: ; preds = %entry, %for.inc
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%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
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%sum.011 = phi i32 [ %sum.1, %for.inc ], [ 0, %entry ]
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%arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
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%0 = load i32, i32* %arrayidx, align 4
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%cmp1 = icmp sgt i32 %0, 30
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br i1 %cmp1, label %if.then, label %for.inc
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if.then: ; preds = %for.body
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%add = add i32 %sum.011, 2
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%add4 = add i32 %add, %0
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br label %for.inc
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for.inc: ; preds = %for.body, %if.then
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%sum.1 = phi i32 [ %add4, %if.then ], [ %sum.011, %for.body ]
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%indvars.iv.next = add i64 %indvars.iv, 1
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%lftr.wideiv = trunc i64 %indvars.iv.next to i32
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%exitcond = icmp eq i32 %lftr.wideiv, %n
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.inc, %entry
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%sum.0.lcssa = phi i32 [ 0, %entry ], [ %sum.1, %for.inc ]
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ret i32 %sum.0.lcssa
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}
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@a = common global [1 x i32*] zeroinitializer, align 8
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@c = common global i32* null, align 8
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; We use to if convert this loop. This is not safe because there is a trapping
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; constant expression.
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; PR16729
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; CHECK-LABEL: trapping_constant_expression
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; CHECK-NOT: or <4 x i32>
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define i32 @trapping_constant_expression() {
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entry:
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br label %for.body
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for.body:
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%inc3 = phi i32 [ 0, %entry ], [ %inc, %cond.end ]
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%or2 = phi i32 [ 0, %entry ], [ %or, %cond.end ]
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br i1 icmp eq (i32** getelementptr inbounds ([1 x i32*], [1 x i32*]* @a, i64 0, i64 0), i32** @c), label %cond.false, label %cond.end
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cond.false:
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br label %cond.end
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cond.end:
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%cond = phi i32 [ sdiv (i32 1, i32 zext (i1 icmp eq (i32** getelementptr inbounds ([1 x i32*], [1 x i32*]* @a, i64 0, i64 0), i32** @c) to i32)), %cond.false ], [ 0, %for.body ]
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%or = or i32 %or2, %cond
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%inc = add nsw i32 %inc3, 1
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%cmp = icmp slt i32 %inc, 128
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br i1 %cmp, label %for.body, label %for.end
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for.end:
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ret i32 %or
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}
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; Neither should we if-convert if there is an instruction operand that is a
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; trapping constant expression.
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; PR16729
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; CHECK-LABEL: trapping_constant_expression2
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; CHECK-NOT: or <4 x i32>
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define i32 @trapping_constant_expression2() {
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entry:
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br label %for.body
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for.body:
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%inc3 = phi i32 [ 0, %entry ], [ %inc, %cond.end ]
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%or2 = phi i32 [ 0, %entry ], [ %or, %cond.end ]
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br i1 icmp eq (i32** getelementptr inbounds ([1 x i32*], [1 x i32*]* @a, i64 0, i64 0), i32** @c), label %cond.false, label %cond.end
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cond.false:
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%cond.1 = or i32 %inc3, sdiv (i32 1, i32 zext (i1 icmp eq (i32** getelementptr inbounds ([1 x i32*], [1 x i32*]* @a, i64 0, i64 1), i32** @c) to i32))
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br label %cond.end
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cond.end:
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%cond = phi i32 [ %cond.1, %cond.false ], [ %inc3, %for.body ]
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%or = or i32 %or2, %cond
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%inc = add nsw i32 %inc3, 1
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%cmp = icmp slt i32 %inc, 128
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br i1 %cmp, label %for.body, label %for.end
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for.end:
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ret i32 %or
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}
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