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llvm-mirror/test/CodeGen/X86/clobber-fi0.ll
Nirav Dave 2e307633f3 [DAG] Improve Aliasing of operations to static alloca
Re-recommiting after landing DAG extension-crash fix.

Recommiting after adding check to avoid miscomputing alias information
on addresses of the same base but different subindices.

Memory accesses offset from frame indices may alias, e.g., we
may merge write from function arguments passed on the stack when they
are contiguous. As a result, when checking aliasing, we consider the
underlying frame index's offset from the stack pointer.

Static allocs are realized as stack objects in SelectionDAG, but its
offset is not set until post-DAG causing DAGCombiner's alias check to
consider access to static allocas to frequently alias. Modify isAlias
to consider access between static allocas and access from other frame
objects to be considered aliasing.

Many test changes are included here. Most are fixes for tests which
indirectly relied on our aliasing ability and needed to be modified to
preserve their original intent.

The remaining tests have minor improvements due to relaxed
ordering. The exception is CodeGen/X86/2011-10-19-widen_vselect.ll
which has a minor degradation dispite though the pre-legalized DAG is
improved.

Reviewers: rnk, mkuper, jonpa, hfinkel, uweigand

Reviewed By: rnk

Subscribers: sdardis, nemanjai, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D33345

llvm-svn: 308350
2017-07-18 20:06:24 +00:00

38 lines
1.6 KiB
LLVM

; RUN: llc < %s -verify-machineinstrs -mcpu=generic -mtriple=x86_64-linux | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.7.0"
; In the code below we need to copy the EFLAGS because of scheduling constraints.
; When copying the EFLAGS we need to write to the stack with push/pop. This forces
; us to emit the prolog.
; CHECK: main
; CHECK: subq{{.*}}rsp
; CHECK: ret
define i32 @main(i32 %arg, i8** %arg1) nounwind {
bb:
%tmp = alloca i32, align 4 ; [#uses=3 type=i32*]
%tmp2 = alloca i32, align 4 ; [#uses=3 type=i32*]
%tmp3 = alloca i32 ; [#uses=1 type=i32*]
store volatile i32 1, i32* %tmp, align 4
store volatile i32 1, i32* %tmp2, align 4
br label %bb4
bb4: ; preds = %bb4, %bb
%tmp6 = load volatile i32, i32* %tmp2, align 4 ; [#uses=1 type=i32]
%tmp7 = add i32 %tmp6, -1 ; [#uses=2 type=i32]
store volatile i32 %tmp7, i32* %tmp2, align 4
%tmp8 = icmp eq i32 %tmp7, 0 ; [#uses=1 type=i1]
%tmp9 = load volatile i32, i32* %tmp ; [#uses=1 type=i32]
%tmp10 = add i32 %tmp9, -1 ; [#uses=1 type=i32]
store volatile i32 %tmp10, i32* %tmp3
br i1 %tmp8, label %bb11, label %bb4
bb11: ; preds = %bb4
%tmp12 = load volatile i32, i32* %tmp, align 4 ; [#uses=1 type=i32]
ret i32 %tmp12
}