Serguei Katkov a701b7e368 [CGP] Remove dead PHI nodes before elimination of mostly empty blocks
Before elimination of mostly empty block it makes sense to remove dead PHI nodes.
It open more opportunity for elimination plus eliminates dead code itself.

It appeared that change results in failing many unit tests and some of
them I've updated and for another one I disable this optimization.
The pattern I observed in the tests is that there is a infinite loop
without side effects. As a result after elimination of dead phi node all other
related instruction are also removed and tests stops to check what it is expected.

Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D158503
2023-08-29 04:35:06 +00:00

37 lines
1.2 KiB
LLVM

; REQUIRES: asserts
; RUN: llc < %s -mtriple=powerpc64le-unknown-linux-gnu -verify-machineinstrs\
; RUN: -mcpu=pwr9 --ppc-enable-pipeliner -debug-only=pipeliner -disable-cgp-delete-phis 2>&1 \
; RUN: >/dev/null | FileCheck %s
%0 = type { i32, [16 x double] }
; CHECK: MII = 3 MAX_II = 13 (rec=3, res=2)
define dso_local fastcc double @_ZN3povL9polysolveEiPdS0_() unnamed_addr #0 {
br label %1
1: ; preds = %1, %0
br i1 undef, label %2, label %1
2: ; preds = %1
br i1 undef, label %14, label %3
3: ; preds = %3, %2
%4 = phi i64 [ %7, %3 ], [ undef, %2 ]
%5 = phi double [ %11, %3 ], [ undef, %2 ]
%6 = phi i64 [ %12, %3 ], [ undef, %2 ]
%7 = add nsw i64 %4, -1
%8 = fmul fast double %5, 1.000000e+07
%9 = getelementptr inbounds %0, ptr null, i64 1, i32 1, i64 %7
%10 = load double, ptr %9, align 8
%11 = fadd fast double %10, %8
%12 = add i64 %6, -1
%13 = icmp eq i64 %12, 0
br i1 %13, label %14, label %3
14: ; preds = %3, %2
%15 = phi double [ undef, %2 ], [ %11, %3 ]
%16 = fmul fast double %15, undef
ret double %16
}