Re-implement the main strength-reduction portion of LoopStrengthReduction.
This new version is much more aggressive about doing "full" reduction in
cases where it reduces register pressure, and also more aggressive about
rewriting induction variables to count down (or up) to zero when doing so
reduces register pressure.
It currently uses fairly simplistic algorithms for finding reuse
opportunities, but it introduces a new framework allows it to combine
multiple strategies at once to form hybrid solutions, instead of doing
all full-reduction or all base+index.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94061 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/ARM/arm-negative-stride.ll b/test/CodeGen/ARM/arm-negative-stride.ll
index 72ec8ef..52ab871 100644
--- a/test/CodeGen/ARM/arm-negative-stride.ll
+++ b/test/CodeGen/ARM/arm-negative-stride.ll
@@ -1,7 +1,32 @@
; RUN: llc < %s -march=arm | FileCheck %s
+; This loop is rewritten with an indvar which counts down, which
+; frees up a register from holding the trip count.
+
define void @test(i32* %P, i32 %A, i32 %i) nounwind {
entry:
+; CHECK: str r1, [{{r.*}}, +{{r.*}}, lsl #2]
+ icmp eq i32 %i, 0 ; <i1>:0 [#uses=1]
+ br i1 %0, label %return, label %bb
+
+bb: ; preds = %bb, %entry
+ %indvar = phi i32 [ 0, %entry ], [ %indvar.next, %bb ] ; <i32> [#uses=2]
+ %i_addr.09.0 = sub i32 %i, %indvar ; <i32> [#uses=1]
+ %tmp2 = getelementptr i32* %P, i32 %i_addr.09.0 ; <i32*> [#uses=1]
+ store i32 %A, i32* %tmp2
+ %indvar.next = add i32 %indvar, 1 ; <i32> [#uses=2]
+ icmp eq i32 %indvar.next, %i ; <i1>:1 [#uses=1]
+ br i1 %1, label %return, label %bb
+
+return: ; preds = %bb, %entry
+ ret void
+}
+
+; This loop has a non-address use of the count-up indvar, so
+; it'll remain. Now the original store uses a negative-stride address.
+
+define void @test_with_forced_iv(i32* %P, i32 %A, i32 %i) nounwind {
+entry:
; CHECK: str r1, [{{r.*}}, -{{r.*}}, lsl #2]
icmp eq i32 %i, 0 ; <i1>:0 [#uses=1]
br i1 %0, label %return, label %bb
@@ -11,6 +36,7 @@
%i_addr.09.0 = sub i32 %i, %indvar ; <i32> [#uses=1]
%tmp2 = getelementptr i32* %P, i32 %i_addr.09.0 ; <i32*> [#uses=1]
store i32 %A, i32* %tmp2
+ store i32 %indvar, i32* null
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=2]
icmp eq i32 %indvar.next, %i ; <i1>:1 [#uses=1]
br i1 %1, label %return, label %bb
diff --git a/test/CodeGen/ARM/lsr-code-insertion.ll b/test/CodeGen/ARM/lsr-code-insertion.ll
index 507ec2c..1bbb96d 100644
--- a/test/CodeGen/ARM/lsr-code-insertion.ll
+++ b/test/CodeGen/ARM/lsr-code-insertion.ll
@@ -1,5 +1,5 @@
-; RUN: llc < %s -stats |& grep {40.*Number of machine instrs printed}
-; RUN: llc < %s -stats |& grep {.*Number of re-materialization}
+; RUN: llc < %s -stats |& grep {39.*Number of machine instrs printed}
+; RUN: llc < %s -stats |& not grep {.*Number of re-materialization}
; This test really wants to check that the resultant "cond_true" block only
; has a single store in it, and that cond_true55 only has code to materialize
; the constant and do a store. We do *not* want something like this:
diff --git a/test/CodeGen/ARM/remat.ll b/test/CodeGen/ARM/remat.ll
index 9565c8b..9072bcb 100644
--- a/test/CodeGen/ARM/remat.ll
+++ b/test/CodeGen/ARM/remat.ll
@@ -1,5 +1,4 @@
-; RUN: llc < %s -mtriple=arm-apple-darwin
-; RUN: llc < %s -mtriple=arm-apple-darwin -stats -info-output-file - | grep "Number of re-materialization" | grep 3
+; RUN: llc < %s -mtriple=arm-apple-darwin -stats -info-output-file - | not grep "Number of re-materialization"
%struct.CONTENTBOX = type { i32, i32, i32, i32, i32 }
%struct.LOCBOX = type { i32, i32, i32, i32 }