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llvm-project/llvm/test/CodeGen/NVPTX/machine-sink.ll

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[MachineSink] Use the real post dominator tree Summary: Fixes a FIXME in MachineSinking. Instead of using the simple heuristics in isPostDominatedBy, use the real MachinePostDominatorTree and MachineLoopInfo. The old heuristics caused instructions to sink unnecessarily, and might create register pressure. This is the second try of the fix. The first one (D4814) caused a performance regression due to failing to sink instructions out of loops (PR21115). This patch fixes PR21115 by sinking an instruction from a deeper loop to a shallower one regardless of whether the target block post-dominates the source. Thanks Alexey Volkov for reporting PR21115! Test Plan: Added a NVPTX codegen test to verify that our change prevents the backend from over-sinking. It also shows the unnecessary register pressure caused by over-sinking. Added an X86 test to verify we can sink instructions out of loops regardless of the dominance relationship. This test is reduced from Alexey's test in PR21115. Updated an affected test in X86. Also ran SPEC CINT2006 and llvm-test-suite for compilation time and runtime performance. Results are attached separately in the review thread. Reviewers: Jiangning, resistor, hfinkel Reviewed By: hfinkel Subscribers: hfinkel, bruno, volkalexey, llvm-commits, meheff, eliben, jholewinski Differential Revision: http://reviews.llvm.org/D5633 llvm-svn: 219773
2014-10-15 11:27:43 +08:00
; RUN: llc < %s -march=nvptx -mcpu=sm_20 | FileCheck %s
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64"
@scalar1 = internal addrspace(3) global float 0.000000e+00, align 4
@scalar2 = internal addrspace(3) global float 0.000000e+00, align 4
; We shouldn't sink mul.rn.f32 to BB %merge because BB %merge post-dominates
; BB %entry. Over-sinking created more register pressure on this example. The
; backend would sink the fmuls to BB %merge, but not the loads for being
; conservative on sinking memory accesses. As a result, the loads and
; the two fmuls would be separated to two basic blocks, causing two
; cross-BB live ranges.
define float @post_dominate(float %x, i1 %cond) {
; CHECK-LABEL: post_dominate(
entry:
[opaque pointer type] Add textual IR support for explicit type parameter to load instruction Essentially the same as the GEP change in r230786. A similar migration script can be used to update test cases, though a few more test case improvements/changes were required this time around: (r229269-r229278) import fileinput import sys import re pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)") for line in sys.stdin: sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line)) Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7649 llvm-svn: 230794
2015-02-28 05:17:42 +08:00
%0 = load float, float* addrspacecast (float addrspace(3)* @scalar1 to float*), align 4
%1 = load float, float* addrspacecast (float addrspace(3)* @scalar2 to float*), align 4
[MachineSink] Use the real post dominator tree Summary: Fixes a FIXME in MachineSinking. Instead of using the simple heuristics in isPostDominatedBy, use the real MachinePostDominatorTree and MachineLoopInfo. The old heuristics caused instructions to sink unnecessarily, and might create register pressure. This is the second try of the fix. The first one (D4814) caused a performance regression due to failing to sink instructions out of loops (PR21115). This patch fixes PR21115 by sinking an instruction from a deeper loop to a shallower one regardless of whether the target block post-dominates the source. Thanks Alexey Volkov for reporting PR21115! Test Plan: Added a NVPTX codegen test to verify that our change prevents the backend from over-sinking. It also shows the unnecessary register pressure caused by over-sinking. Added an X86 test to verify we can sink instructions out of loops regardless of the dominance relationship. This test is reduced from Alexey's test in PR21115. Updated an affected test in X86. Also ran SPEC CINT2006 and llvm-test-suite for compilation time and runtime performance. Results are attached separately in the review thread. Reviewers: Jiangning, resistor, hfinkel Reviewed By: hfinkel Subscribers: hfinkel, bruno, volkalexey, llvm-commits, meheff, eliben, jholewinski Differential Revision: http://reviews.llvm.org/D5633 llvm-svn: 219773
2014-10-15 11:27:43 +08:00
; CHECK: ld.shared.f32
; CHECK: ld.shared.f32
%2 = fmul float %0, %0
%3 = fmul float %1, %2
; CHECK-NOT: bra
; CHECK: mul.rn.f32
; CHECK: mul.rn.f32
br i1 %cond, label %then, label %merge
then:
%z = fadd float %x, %x
br label %then2
then2:
%z2 = fadd float %z, %z
br label %merge
merge:
%y = phi float [ 0.0, %entry ], [ %z2, %then2 ]
%w = fadd float %y, %3
ret float %w
}