caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
be1294de9dd93ae02002bd1aa4b4a8d62e562c21
clang-p2996/llvm/test/Transforms/LICM/promote-capture.ll
Djordje Todorovic 2cdc6f2ca6 Reland "[LICM] Hoist LOAD without sinking the STORE" 
When doing load/store promotion within LICM, if we
cannot prove that it is safe to sink the store we won't
hoist the load, even though we can prove the load could
be dereferenced and moved outside the loop. This patch
implements the load promotion by moving it in the loop
preheader by inserting proper PHI in the loop. The store
is kept as is in the loop. By doing this, we avoid doing
the load from a memory location in each iteration.

Please consider this small example:

loop {
  var = *ptr;
  if (var) break;
  *ptr= var + 1;
}
After this patch, it will be:

var0 = *ptr;
loop {
  var1 = phi (var0, var2);
  if (var1) break;
  var2 = var1 + 1;
  *ptr = var2;
}
This addresses some problems from [0].

[0] https://bugs.llvm.org/show_bug.cgi?id=51193

Differential revision: https://reviews.llvm.org/D113289
2021-12-02 03:53:50 -08:00

158 lines
5.1 KiB
LLVM
Raw Blame History

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -passes='loop-mssa(licm)' < %s | FileCheck %s
declare i1 @cond(i32 %v) readnone
declare void @capture(i32* %p) readnone
define void @test_captured_after_loop(i32 %len) {
; CHECK-LABEL: @test_captured_after_loop(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[COUNT:%.*]] = alloca i32, align 4
; CHECK-NEXT: store i32 0, i32* [[COUNT]], align 4
; CHECK-NEXT: [[COUNT_PROMOTED:%.*]] = load i32, i32* [[COUNT]], align 4
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[C_INC2:%.*]] = phi i32 [ [[COUNT_PROMOTED]], [[ENTRY:%.*]] ], [ [[C_INC1:%.*]], [[LATCH:%.*]] ]
; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[I_NEXT:%.*]], [[LATCH]] ]
; CHECK-NEXT: [[COND:%.*]] = call i1 @cond(i32 [[I]])
; CHECK-NEXT: br i1 [[COND]], label [[IF:%.*]], label [[LATCH]]
; CHECK: if:
; CHECK-NEXT: [[C_INC:%.*]] = add i32 [[C_INC2]], 1
; CHECK-NEXT: br label [[LATCH]]
; CHECK: latch:
; CHECK-NEXT: [[C_INC1]] = phi i32 [ [[C_INC]], [[IF]] ], [ [[C_INC2]], [[LOOP]] ]
; CHECK-NEXT: [[I_NEXT]] = add nuw i32 [[I]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[I_NEXT]], [[LEN:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[EXIT:%.*]], label [[LOOP]]
; CHECK: exit:
; CHECK-NEXT: [[C_INC1_LCSSA:%.*]] = phi i32 [ [[C_INC1]], [[LATCH]] ]
; CHECK-NEXT: store i32 [[C_INC1_LCSSA]], i32* [[COUNT]], align 4
; CHECK-NEXT: call void @capture(i32* [[COUNT]])
; CHECK-NEXT: ret void
;
entry:
%count = alloca i32
store i32 0, i32* %count
br label %loop
loop:
%i = phi i32 [ 0, %entry ], [ %i.next, %latch ]
%cond = call i1 @cond(i32 %i)
br i1 %cond, label %if, label %latch
if:
%c = load i32, i32* %count
%c.inc = add i32 %c, 1
store i32 %c.inc, i32* %count
br label %latch
latch:
%i.next = add nuw i32 %i, 1
%cmp = icmp eq i32 %i.next, %len
br i1 %cmp, label %exit, label %loop
exit:
call void @capture(i32* %count)
ret void
}
define void @test_captured_in_loop(i32 %len) {
; CHECK-LABEL: @test_captured_in_loop(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[COUNT:%.*]] = alloca i32, align 4
; CHECK-NEXT: store i32 0, i32* [[COUNT]], align 4
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[I_NEXT:%.*]], [[LATCH:%.*]] ]
; CHECK-NEXT: [[COND:%.*]] = call i1 @cond(i32 [[I]])
; CHECK-NEXT: br i1 [[COND]], label [[IF:%.*]], label [[LATCH]]
; CHECK: if:
; CHECK-NEXT: [[C:%.*]] = load i32, i32* [[COUNT]], align 4
; CHECK-NEXT: [[C_INC:%.*]] = add i32 [[C]], 1
; CHECK-NEXT: store i32 [[C_INC]], i32* [[COUNT]], align 4
; CHECK-NEXT: call void @capture(i32* [[COUNT]])
; CHECK-NEXT: br label [[LATCH]]
; CHECK: latch:
; CHECK-NEXT: [[I_NEXT]] = add nuw i32 [[I]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[I_NEXT]], [[LEN:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[EXIT:%.*]], label [[LOOP]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%count = alloca i32
store i32 0, i32* %count
br label %loop
loop:
%i = phi i32 [ 0, %entry ], [ %i.next, %latch ]
%cond = call i1 @cond(i32 %i)
br i1 %cond, label %if, label %latch
if:
%c = load i32, i32* %count
%c.inc = add i32 %c, 1
store i32 %c.inc, i32* %count
call void @capture(i32* %count)
br label %latch
latch:
%i.next = add nuw i32 %i, 1
%cmp = icmp eq i32 %i.next, %len
br i1 %cmp, label %exit, label %loop
exit:
ret void
}
define void @test_captured_before_loop(i32 %len) {
; CHECK-LABEL: @test_captured_before_loop(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[COUNT:%.*]] = alloca i32, align 4
; CHECK-NEXT: store i32 0, i32* [[COUNT]], align 4
; CHECK-NEXT: call void @capture(i32* [[COUNT]])
; CHECK-NEXT: [[COUNT_PROMOTED:%.*]] = load i32, i32* [[COUNT]], align 4
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[C_INC2:%.*]] = phi i32 [ [[COUNT_PROMOTED]], [[ENTRY:%.*]] ], [ [[C_INC1:%.*]], [[LATCH:%.*]] ]
; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[I_NEXT:%.*]], [[LATCH]] ]
; CHECK-NEXT: [[COND:%.*]] = call i1 @cond(i32 [[I]])
; CHECK-NEXT: br i1 [[COND]], label [[IF:%.*]], label [[LATCH]]
; CHECK: if:
; CHECK-NEXT: [[C_INC:%.*]] = add i32 [[C_INC2]], 1
; CHECK-NEXT: store i32 [[C_INC]], i32* [[COUNT]], align 4
; CHECK-NEXT: br label [[LATCH]]
; CHECK: latch:
; CHECK-NEXT: [[C_INC1]] = phi i32 [ [[C_INC]], [[IF]] ], [ [[C_INC2]], [[LOOP]] ]
; CHECK-NEXT: [[I_NEXT]] = add nuw i32 [[I]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[I_NEXT]], [[LEN:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[EXIT:%.*]], label [[LOOP]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%count = alloca i32
store i32 0, i32* %count
call void @capture(i32* %count)
br label %loop
loop:
%i = phi i32 [ 0, %entry ], [ %i.next, %latch ]
%cond = call i1 @cond(i32 %i)
br i1 %cond, label %if, label %latch
if:
%c = load i32, i32* %count
%c.inc = add i32 %c, 1
store i32 %c.inc, i32* %count
br label %latch
latch:
%i.next = add nuw i32 %i, 1
%cmp = icmp eq i32 %i.next, %len
br i1 %cmp, label %exit, label %loop
exit:
ret void
}
Reference in New Issue View Git Blame Copy Permalink