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9d48c2760c
This patch implements getSmallConstantTripMultiple(L) correctly for multiple exit loops. The previous implementation was both imprecise, and violated the specified behavior of the method. This was fine in practice, because it turns out the function was both dead in real code, and not tested for the multiple exit case. Differential Revision: https://reviews.llvm.org/D103189
151 lines
4.3 KiB
LLVM
151 lines
4.3 KiB
LLVM
; RUN: opt -S -analyze -enable-new-pm=0 -scalar-evolution < %s 2>&1 | FileCheck %s
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; RUN: opt -S -disable-output "-passes=print<scalar-evolution>" < %s 2>&1 2>&1 | FileCheck %s
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; umin is represented using -1 * umax in scalar evolution. -1 is considered as the
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; constant of the multiply expression (-1 * ((-1 + (-1 * %a)) umax (-1 + (-1 * %b)))).
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; Returns the greatest power of 2 divisor by evaluating the minimal trailing zeros
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; for the trip count expression.
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;
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; int foo(uint32_t a, uint32_t b, uint32_t *c) {
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; for (uint32_t i = 0; i < (uint32_t)(a < b ? a : b) + 1; i++)
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; c[i] = i;
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; return 0;
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; }
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;
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; CHECK: Loop %for.body: Trip multiple is 1
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define i32 @foo(i32 %a, i32 %b, i32* %c) {
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entry:
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%cmp = icmp ult i32 %a, %b
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%cond = select i1 %cmp, i32 %a, i32 %b
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%add = add i32 %cond, 1
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%cmp18 = icmp eq i32 %add, 0
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br i1 %cmp18, label %for.cond.cleanup, label %for.body.preheader
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for.body.preheader: ; preds = %entry
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br label %for.body
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for.cond.cleanup.loopexit: ; preds = %for.body
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br label %for.cond.cleanup
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for.cond.cleanup: ; preds = %for.cond.cleanup.loopexit, %entry
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ret i32 0
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for.body: ; preds = %for.body.preheader, %for.body
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%i.09 = phi i32 [ %inc, %for.body ], [ 0, %for.body.preheader ]
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%arrayidx = getelementptr inbounds i32, i32* %c, i32 %i.09
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store i32 %i.09, i32* %arrayidx, align 4
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%inc = add nuw i32 %i.09, 1
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%cmp1 = icmp ult i32 %inc, %add
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br i1 %cmp1, label %for.body, label %for.cond.cleanup.loopexit
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}
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; Overflow may happen for the multiply expression n * 3, verify that trip
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; multiple is set to 1 if NUW/NSW are not set.
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;
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; __attribute__((noinline)) void a(unsigned n) {
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; #pragma unroll(3)
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; for (unsigned i = 0; i != n * 3; ++i)
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; printf("TEST%u\n", i);
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; }
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; int main() { a(2863311531U); }
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;
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; CHECK: Loop %for.body: Trip multiple is 1
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@.str2 = private unnamed_addr constant [8 x i8] c"TEST%u\0A\00", align 1
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define void @foo2(i32 %n) {
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entry:
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%mul = mul i32 %n, 3
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%cmp4 = icmp eq i32 %mul, 0
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br i1 %cmp4, label %for.cond.cleanup, label %for.body.preheader
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for.body.preheader: ; preds = %entry
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br label %for.body
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for.cond.cleanup.loopexit: ; preds = %for.body
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br label %for.cond.cleanup
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for.cond.cleanup: ; preds = %for.cond.cleanup.loopexit, %entry
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ret void
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for.body: ; preds = %for.body.preheader, %for.body
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%i.05 = phi i32 [ %inc, %for.body ], [ 0, %for.body.preheader ]
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%call = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str2, i32 0, i32 0), i32 %i.05)
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%inc = add nuw i32 %i.05, 1
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%cmp = icmp eq i32 %inc, %mul
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br i1 %cmp, label %for.cond.cleanup.loopexit, label %for.body
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}
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declare i32 @printf(i8* nocapture readonly, ...)
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; If we couldn't prove no overflow for the multiply expression 24 * n,
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; returns the greatest power of 2 divisor. If overflows happens
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; the trip count is still divisible by the greatest power of 2 divisor.
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;
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; CHECK: Loop %l3: Trip multiple is 8
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declare void @f()
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define i32 @foo3(i32 %n) {
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entry:
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%loop_ctl = mul i32 %n, 24
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br label %l3
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l3:
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%x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
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call void @f()
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%inc = add i32 %x.0, 1
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%exitcond = icmp eq i32 %inc, %loop_ctl
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br i1 %exitcond, label %exit, label %l3
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exit:
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ret i32 0
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}
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; If the trip count is a constant, verify that we obtained the trip
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; count itself. For huge trip counts, or zero, we return 1.
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;
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; CHECK: Loop %l3: Trip multiple is 3
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define i32 @foo4(i32 %n) {
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entry:
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br label %l3
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l3:
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%x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
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call void @f()
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%inc = add i32 %x.0, 1
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%exitcond = icmp eq i32 %inc, 3
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br i1 %exitcond, label %exit, label %l3
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exit:
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ret i32 0
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}
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; If there are multiple exits, the result is the GCD of the multiples
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; of each individual exit (since we don't know which is taken).
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; CHECK: Loop %l4: Trip multiple is 50
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define i32 @foo5(i32 %n) {
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entry:
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br label %l4
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l4:
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%x.0 = phi i32 [ 0, %entry ], [ %inc, %l4-latch ]
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call void @f()
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%inc = add i32 %x.0, 1
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%earlycond = icmp eq i32 %inc, 150
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br i1 %earlycond, label %exit, label %l4-latch
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l4-latch:
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%exitcond = icmp eq i32 %inc, 200
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br i1 %exitcond, label %exit, label %l4
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exit:
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ret i32 0
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}
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