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llvm-project/llvm/test/Transforms/HardwareLoops/ARM/fp-emulation.ll
David Green b2ac9681a7 [ARM] Alter t2DoLoopStart to define lr 
This changes the definition of t2DoLoopStart from
t2DoLoopStart rGPR
to
GPRlr = t2DoLoopStart rGPR

This will hopefully mean that low overhead loops are more tied together,
and we can more reliably generate loops without reverting or being at
the whims of the register allocator.

This is a fairly simple change in itself, but leads to a number of other
required alterations.

 - The hardware loop pass, if UsePhi is set, now generates loops of the
   form:
       %start = llvm.start.loop.iterations(%N)
     loop:
       %p = phi [%start], [%dec]
       %dec = llvm.loop.decrement.reg(%p, 1)
       %c = icmp ne %dec, 0
       br %c, loop, exit
 - For this a new llvm.start.loop.iterations intrinsic was added, identical
   to llvm.set.loop.iterations but produces a value as seen above, gluing
   the loop together more through def-use chains.
 - This new instrinsic conceptually produces the same output as input,
   which is taught to SCEV so that the checks in MVETailPredication are not
   affected.
 - Some minor changes are needed to the ARMLowOverheadLoop pass, but it has
   been left mostly as before. We should now more reliably be able to tell
   that the t2DoLoopStart is correct without having to prove it, but
   t2WhileLoopStart and tail-predicated loops will remain the same.
 - And all the tests have been updated. There are a lot of them!

This patch on it's own might cause more trouble that it helps, with more
tail-predicated loops being reverted, but some additional patches can
hopefully improve upon that to get to something that is better overall.

Differential Revision: https://reviews.llvm.org/D89881
2020-11-10 15:57:58 +00:00

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; RUN: opt -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+fp-armv8 -hardware-loops %s -S -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-FP
; RUN: opt -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+soft-float -hardware-loops %s -S -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-SOFT
; CHECK-LABEL: test_fptosi
; CHECK-SOFT-NOT: call i32 @llvm.start.loop.iterations
; CHECK: entry:
; CHECK-FP: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
; CHECK-FP: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
; CHECK: while.body.lr.ph:
; CHECK-FP: [[START:%[^ ]+]] = call i32 @llvm.start.loop.iterations.i32(i32 [[COUNT]])
; CHECK-FP-NEXT: br label %while.body
; CHECK-FP: [[REM:%[^ ]+]] = phi i32 [ [[START]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
; CHECK-FP: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32(i32 [[REM]], i32 1)
; CHECK-FP: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
; CHECK-FP: br i1 [[CMP]], label %while.body, label %cleanup.loopexit
define void @test_fptosi(i32 %n, i32** %g, double** %d) {
entry:
%n.off = add i32 %n, -1
%0 = icmp ult i32 %n.off, 500
br i1 %0, label %while.body.lr.ph, label %cleanup
while.body.lr.ph:
%1 = load double*, double** %d, align 4
%2 = load i32*, i32** %g, align 4
br label %while.body
while.body:
%i.012 = phi i32 [ 0, %while.body.lr.ph ], [ %inc, %if.end4 ]
%rem = urem i32 %i.012, 10
%tobool = icmp eq i32 %rem, 0
br i1 %tobool, label %if.end4, label %if.then2
if.then2:
%arrayidx = getelementptr inbounds double, double* %1, i32 %i.012
%3 = load double, double* %arrayidx, align 8
%conv = fptosi double %3 to i32
%arrayidx3 = getelementptr inbounds i32, i32* %2, i32 %i.012
store i32 %conv, i32* %arrayidx3, align 4
br label %if.end4
if.end4:
%inc = add nuw i32 %i.012, 1
%cmp1 = icmp ult i32 %inc, %n
br i1 %cmp1, label %while.body, label %cleanup.loopexit
cleanup.loopexit:
br label %cleanup
cleanup:
ret void
}
; CHECK-LABEL: test_fptoui
; CHECK: entry:
; CHECK-FP: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
; CHECK-FP: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
; CHECK-FP: while.body.lr.ph:
; CHECK-FP: [[START:%[^ ]+]] = call i32 @llvm.start.loop.iterations.i32(i32 [[COUNT]])
; CHECK-FP-NEXT: br label %while.body
; CHECK-FP: [[REM:%[^ ]+]] = phi i32 [ [[START]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
; CHECK-FP: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32(i32 [[REM]], i32 1)
; CHECK-FP: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
; CHECK-FP: br i1 [[CMP]], label %while.body, label %cleanup.loopexit
; CHECK-SOFT-NOT: call i32 @llvm.start.loop.iterations
define void @test_fptoui(i32 %n, i32** %g, double** %d) {
entry:
%n.off = add i32 %n, -1
%0 = icmp ult i32 %n.off, 500
br i1 %0, label %while.body.lr.ph, label %cleanup
while.body.lr.ph:
%1 = load double*, double** %d, align 4
%2 = load i32*, i32** %g, align 4
br label %while.body
while.body:
%i.012 = phi i32 [ 0, %while.body.lr.ph ], [ %inc, %if.end4 ]
%rem = urem i32 %i.012, 10
%tobool = icmp eq i32 %rem, 0
br i1 %tobool, label %if.end4, label %if.then2
if.then2:
%arrayidx = getelementptr inbounds double, double* %1, i32 %i.012
%3 = load double, double* %arrayidx, align 8
%conv = fptoui double %3 to i32
%arrayidx3 = getelementptr inbounds i32, i32* %2, i32 %i.012
store i32 %conv, i32* %arrayidx3, align 4
br label %if.end4
if.end4:
%inc = add nuw i32 %i.012, 1
%cmp1 = icmp ult i32 %inc, %n
br i1 %cmp1, label %while.body, label %cleanup.loopexit
cleanup.loopexit:
br label %cleanup
cleanup:
ret void
}
; CHECK-LABEL: load_store_float
; CHECK: entry:
; CHECK: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
; CHECK: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
; CHECK: while.body.lr.ph:
; CHECK: [[START:%[^ ]+]] = call i32 @llvm.start.loop.iterations.i32(i32 [[COUNT]])
; CHECK-NEXT: br label %while.body
; CHECK: [[REM:%[^ ]+]] = phi i32 [ [[START]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32(i32 [[REM]], i32 1)
; CHECK: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
; CHECK: br i1 [[CMP]], label %while.body, label %cleanup.loopexit
define void @load_store_float(i32 %n, double** %d, double** %g) {
entry:
%n.off = add i32 %n, -1
%0 = icmp ult i32 %n.off, 500
br i1 %0, label %while.body.lr.ph, label %cleanup
while.body.lr.ph:
%1 = load double*, double** %d, align 4
%2 = load double*, double** %g, align 4
br label %while.body
while.body:
%i.012 = phi i32 [ 0, %while.body.lr.ph ], [ %inc, %if.end4 ]
%rem = urem i32 %i.012, 10
%tobool = icmp eq i32 %rem, 0
br i1 %tobool, label %if.end4, label %if.then2
if.then2:
%arrayidx = getelementptr inbounds double, double* %1, i32 %i.012
%3 = load double, double* %arrayidx, align 8
%arrayidx3 = getelementptr inbounds double, double* %2, i32 %i.012
store double %3, double* %arrayidx3, align 8
br label %if.end4
if.end4:
%inc = add nuw i32 %i.012, 1
%cmp1 = icmp ult i32 %inc, %n
br i1 %cmp1, label %while.body, label %cleanup.loopexit
cleanup.loopexit:
br label %cleanup
cleanup:
ret void
}
; CHECK-LABEL: fp_add
; CHECK-SOFT-NOT: call i32 @llvm.start.loop.iterations
; CHECK: entry:
; CHECK-FP: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
; CHECK-FP: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
; CHECK: while.body.lr.ph:
; CHECK-FP: [[START:%[^ ]+]] = call i32 @llvm.start.loop.iterations.i32(i32 [[COUNT]])
; CHECK: br label %while.body
; CHECK-SOFT-NOT: call i32 @llvm.loop.decrement
; CHECK-FP: [[REM:%[^ ]+]] = phi i32 [ [[START]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
; CHECK-FP: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32(i32 [[REM]], i32 1)
; CHECK-FP: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
; CHECK-FP: br i1 [[CMP]], label %while.body, label %cleanup.loopexit
define void @fp_add(i32 %n, float** %d, float** %g) {
entry:
%n.off = add i32 %n, -1
%0 = icmp ult i32 %n.off, 500
br i1 %0, label %while.body.lr.ph, label %cleanup
while.body.lr.ph:
%1 = load float*, float** %d, align 4
%2 = load float*, float** %g, align 4
br label %while.body
while.body:
%i.012 = phi i32 [ 0, %while.body.lr.ph ], [ %inc, %if.end4 ]
%rem = urem i32 %i.012, 10
%tobool = icmp eq i32 %rem, 0
br i1 %tobool, label %if.end4, label %if.then2
if.then2:
%arrayidx = getelementptr inbounds float, float* %1, i32 %i.012
%3 = load float, float* %arrayidx, align 4
%arrayidx3 = getelementptr inbounds float, float* %2, i32 %i.012
%4 = load float, float* %arrayidx3, align 4
%add = fadd float %3, %4
store float %add, float* %arrayidx3, align 4
br label %if.end4
if.end4:
%inc = add nuw i32 %i.012, 1
%cmp1 = icmp ult i32 %inc, %n
br i1 %cmp1, label %while.body, label %cleanup.loopexit
cleanup.loopexit:
br label %cleanup
cleanup:
ret void
}
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