[llvm] [LoopUnroll] Bound automatic full-unroll cloning work (PR #211683)

[Justin Fargnoli via llvm-commits]

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@@ -0,0 +1,149 @@
+; RUN: opt < %s -passes='default<O2>' -disable-output
+; RUN: opt < %s -passes='require<opt-remark-emit>,loop(loop-unroll-full)' \
+; RUN:   -unroll-full-max-cloned-instructions=1 -unroll-peel-count=0 -S \
+; RUN:   | FileCheck %s
+; RUN: opt < %s -passes=loop-unroll \
+; RUN:   -unroll-full-max-cloned-instructions=35 -unroll-peel-count=0 -S \
+; RUN:   | FileCheck %s --check-prefix=BELOW
+; RUN: opt < %s -passes=loop-unroll \
+; RUN:   -unroll-full-max-cloned-instructions=36 -unroll-peel-count=0 -S \
+; RUN:   | FileCheck %s --check-prefix=AT
+; RUN: opt < %s -passes=loop-unroll \
+; RUN:   -unroll-full-max-cloned-instructions=1 -unroll-peel-count=0 -S \
+; RUN:   | FileCheck %s --check-prefix=EXPLICIT
+; RUN: llvm-extract -func=boundary %s -S \
+; RUN:   | opt -passes=loop-unroll -unroll-full-max-cloned-instructions=1 \
+; RUN:     -unroll-threshold=4294967295 -unroll-peel-count=0 -S \
+; RUN:   | FileCheck %s --check-prefix=NO-THRESHOLD
+;
+; CHECK-LABEL: define void @nested(
+; CHECK: loop.5:
+; CHECK: %iv.5 = phi i64
+;
+; BELOW-LABEL: define i32 @boundary(
+; BELOW: loop:
+; BELOW: %iv = phi i32
+;
+; AT-LABEL: define i32 @boundary(
+; AT-NOT: phi
+; AT: ret i32 10
+;
+; EXPLICIT-LABEL: define i32 @explicit_enable(
+; EXPLICIT-NOT: phi
+; EXPLICIT: ret i32 10
+;
+; NO-THRESHOLD-LABEL: define i32 @boundary(
+; NO-THRESHOLD-NOT: phi
+; NO-THRESHOLD: ret i32 10
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @boundary() {
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %next, %loop ]
+  %next = add i32 %iv, 1
+  %continue = icmp ult i32 %next, 10
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  ret i32 %next
+}
+
+define i32 @explicit_enable() {
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %next, %loop ]
+  %next = add i32 %iv, 1
+  %continue = icmp ult i32 %next, 10
+  br i1 %continue, label %loop, label %exit, !llvm.loop !0
+
+exit:
+  ret i32 %next
+}
+
+define void @nested(i32 %arg) {
+entry:
+  br label %loop.1
+
+loop.1:
+  %iv.1 = phi i64 [ %next.1, %loop.1.latch ], [ 0, %entry ]
+  %cmp.1 = icmp slt i64 %iv.1, 10
+  br i1 %cmp.1, label %loop.2, label %exit
+
+loop.2:
+  %iv.2 = phi i64 [ %next.2, %loop.2.latch ], [ 0, %loop.1 ]
+  %value.2 = phi i32 [ %next.value.2, %loop.2.latch ], [ 0, %loop.1 ]
+  %cmp.2 = icmp slt i64 %iv.2, 10
+  br i1 %cmp.2, label %body.2, label %loop.1.latch
+
+body.2:
+  %next.value.2 = add i32 %value.2, 1
+  %enter.3 = icmp slt i32 %value.2, 0
+  br i1 %enter.3, label %loop.3, label %loop.2.latch
+
+loop.3:
+  %iv.3 = phi i64 [ %next.3, %loop.3.latch ], [ 0, %body.2 ]
+  %cmp.3 = icmp slt i64 %iv.3, 10
+  br i1 %cmp.3, label %loop.4, label %loop.2.latch
+
+loop.4:
+  %iv.4 = phi i64 [ %next.4, %loop.4.latch ], [ 0, %loop.3 ]
+  %value.4 = phi i32 [ %next.value.4, %loop.4.latch ], [ 0, %loop.3 ]
+  %cmp.4 = icmp slt i64 %iv.4, 10
+  br i1 %cmp.4, label %body.4, label %loop.3.latch
+
+body.4:
+  %next.value.4 = add i32 %value.4, 1
+  %enter.5 = icmp slt i32 %value.4, 0
+  br i1 %enter.5, label %loop.5, label %loop.4.latch
+
+loop.5:
+  %iv.5 = phi i64 [ %next.5, %body.5 ], [ 0, %body.4 ]
+  %value.5 = phi i32 [ %arg, %body.5 ], [ 0, %body.4 ]
+  %cmp.5 = icmp slt i64 %iv.5, 10
+  br i1 %cmp.5, label %body.5, label %loop.4.latch
+
+body.5:
+  %negative = icmp slt i32 %value.5, 0
+  call void @llvm.assume(i1 %negative)
+  call void @llvm.stackrestore.p0(ptr null)
----------------
justinfargnoli wrote:

> llvm.stackrestore is a side-effecting call so the body still has something to clone;

Let's use something more common, like `store`ing an input argument. 

https://github.com/llvm/llvm-project/pull/211683