[X86] Improvement in CodeGen instruction selection for LEAs (re-applying post required revision changes.)
Summary:
1/ Operand folding during complex pattern matching for LEAs has been
extended, such that it promotes Scale to accommodate similar operand
appearing in the DAG.
e.g.
T1 = A + B
T2 = T1 + 10
T3 = T2 + A
For above DAG rooted at T3, X86AddressMode will no look like
Base = B , Index = A , Scale = 2 , Disp = 10
2/ During OptimizeLEAPass down the pipeline factorization is now performed over LEAs
so that if there is an opportunity then complex LEAs (having 3 operands)
could be factored out.
e.g.
leal 1(%rax,%rcx,1), %rdx
leal 1(%rax,%rcx,2), %rcx
will be factored as following
leal 1(%rax,%rcx,1), %rdx
leal (%rdx,%rcx) , %edx
3/ Aggressive operand folding for AM based selection for LEAs is sensitive to loops,
thus avoiding creation of any complex LEAs within a loop.
Reviewers: lsaba, RKSimon, craig.topper, qcolombet, jmolloy
Reviewed By: lsaba
Subscribers: jmolloy, spatel, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D35014
llvm-svn: 314886
diff --git a/llvm/test/CodeGen/X86/pr34629.ll b/llvm/test/CodeGen/X86/pr34629.ll
index 031b99d..e37f03b 100644
--- a/llvm/test/CodeGen/X86/pr34629.ll
+++ b/llvm/test/CodeGen/X86/pr34629.ll
@@ -13,8 +13,8 @@
; CHECK: # BB#0: # %entry
; CHECK-NEXT: movq {{.*}}(%rip), %rax
; CHECK-NEXT: leaq (%rax,%rax,4), %rcx
+; CHECK-NEXT: leaq (%rcx,%rax,4), %rax
; CHECK-NEXT: negq %rcx
-; CHECK-NEXT: leaq (%rax,%rax,8), %rax
; CHECK-NEXT: leaq (%rax,%rax,4), %rax
; CHECK-NEXT: testq %rax, %rcx
; CHECK-NEXT: je .LBB0_2