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llvm-mirror/test/CodeGen/ARM/avoid-cpsr-rmw.ll
James Molloy b2a8710b5c [SimplifyCFG] Rewrite SinkThenElseCodeToEnd
[Recommitting now an unrelated assertion in SROA is sorted out]

The new version has several advantages:
  1) IMSHO it's more readable and neater
  2) It handles loads and stores properly
  3) It can handle any number of incoming blocks rather than just two. I'll be taking advantage of this in a followup patch.

With this change we can now finally sink load-modify-store idioms such as:

    if (a)
      return *b += 3;
    else
      return *b += 4;

    =>

    %z = load i32, i32* %y
    %.sink = select i1 %a, i32 5, i32 7
    %b = add i32 %z, %.sink
    store i32 %b, i32* %y
    ret i32 %b

When this works for switches it'll be even more powerful.

Round 4. This time we should handle all instructions correctly, and not replace any operands that need to be constant with variables.

This was really hard to determine safely, so the helper function should be put into the Instruction API. I'll do that as a followup.

llvm-svn: 279460
2016-08-22 19:07:15 +00:00

117 lines
4.0 KiB
LLVM

; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=cortex-a9 | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-CORTEX
; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=swift | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-SWIFT
; Avoid some 's' 16-bit instruction which partially update CPSR (and add false
; dependency) when it isn't dependent on last CPSR defining instruction.
; rdar://8928208
define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) nounwind readnone {
entry:
; CHECK-LABEL: t1:
; CHECK-CORTEX: muls [[REG:(r[0-9]+)]], r3, r2
; CHECK-CORTEX-NEXT: mul [[REG2:(r[0-9]+)]], r1, r0
; CHECK-SWIFT: muls [[REG2:(r[0-9]+)]], r1, r0
; CHECK-SWIFT-NEXT: mul [[REG:(r[0-9]+)]], r2, r3
; CHECK-NEXT: muls r0, [[REG]], [[REG2]]
%0 = mul nsw i32 %a, %b
%1 = mul nsw i32 %c, %d
%2 = mul nsw i32 %0, %1
ret i32 %2
}
; Avoid partial CPSR dependency via loop backedge.
; rdar://10357570
define void @t2(i32* nocapture %ptr1, i32* %ptr2, i32 %c) nounwind {
entry:
; CHECK-LABEL: t2:
br label %while.body
while.body:
; CHECK: while.body
; CHECK: mul r{{[0-9]+}}
; CHECK-NOT: muls
%ptr1.addr.09 = phi i32* [ %add.ptr, %while.body ], [ %ptr1, %entry ]
%ptr2.addr.08 = phi i32* [ %incdec.ptr, %while.body ], [ %ptr2, %entry ]
%0 = load i32, i32* %ptr1.addr.09, align 4
%arrayidx1 = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 1
%1 = load i32, i32* %arrayidx1, align 4
%arrayidx3 = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 2
%2 = load i32, i32* %arrayidx3, align 4
%arrayidx4 = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 3
%3 = load i32, i32* %arrayidx4, align 4
%add.ptr = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 4
%mul = mul i32 %1, %0
%mul5 = mul i32 %mul, %2
%mul6 = mul i32 %mul5, %3
store i32 %mul6, i32* %ptr2.addr.08, align 4
%incdec.ptr = getelementptr inbounds i32, i32* %ptr2.addr.08, i32 -1
%tobool = icmp eq i32* %incdec.ptr, null
br i1 %tobool, label %while.end, label %while.body
while.end:
ret void
}
; Allow partial CPSR dependency when code size is the priority.
; rdar://12878928
define void @t3(i32* nocapture %ptr1, i32* %ptr2, i32 %c) nounwind minsize {
entry:
; CHECK-LABEL: t3:
br label %while.body
while.body:
; CHECK: while.body
; CHECK: mul r{{[0-9]+}}
; CHECK: muls
%ptr1.addr.09 = phi i32* [ %add.ptr, %while.body ], [ %ptr1, %entry ]
%ptr2.addr.08 = phi i32* [ %incdec.ptr, %while.body ], [ %ptr2, %entry ]
%0 = load i32, i32* %ptr1.addr.09, align 4
%arrayidx1 = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 1
%1 = load i32, i32* %arrayidx1, align 4
%arrayidx3 = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 2
%2 = load i32, i32* %arrayidx3, align 4
%arrayidx4 = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 3
%3 = load i32, i32* %arrayidx4, align 4
%add.ptr = getelementptr inbounds i32, i32* %ptr1.addr.09, i32 4
%mul = mul i32 %1, %0
%mul5 = mul i32 %mul, %2
%mul6 = mul i32 %mul5, %3
store i32 %mul6, i32* %ptr2.addr.08, align 4
%incdec.ptr = getelementptr inbounds i32, i32* %ptr2.addr.08, i32 -1
%tobool = icmp eq i32* %incdec.ptr, null
br i1 %tobool, label %while.end, label %while.body
while.end:
ret void
}
; Avoid producing tMOVi8 after a high-latency flag-setting operation.
; <rdar://problem/13468102>
define void @t4(i32* nocapture %p, double* nocapture %q) {
entry:
; CHECK: t4
; CHECK: vmrs APSR_nzcv, fpscr
; CHECK: if.then
; CHECK-NOT: movs
%0 = load double, double* %q, align 4
%cmp = fcmp olt double %0, 1.000000e+01
%incdec.ptr1 = getelementptr inbounds i32, i32* %p, i32 1
br i1 %cmp, label %if.then, label %if.else
if.then:
store i32 7, i32* %p, align 4
%incdec.ptr2 = getelementptr inbounds i32, i32* %p, i32 2
store i32 8, i32* %incdec.ptr1, align 4
store i32 9, i32* %incdec.ptr2, align 4
br label %if.end
if.else:
store i32 3, i32* %p, align 4
%incdec.ptr5 = getelementptr inbounds i32, i32* %p, i32 3
store i32 5, i32* %incdec.ptr1, align 4
store i32 6, i32* %incdec.ptr5, align 4
br label %if.end
if.end:
ret void
}