[DAGCombine] Check the uses of negated floating constant and remove the hack

PowerPC hits an assertion due to somewhat the same reason as https://reviews.llvm.org/D70975.
Though there are already some hack, it still failed with some case, when the operand 0 is NOT
a const fp, it is another fma that with const fp. And that const fp is negated which result in multi-uses.

A better fix is to check the uses of the negated const fp. If there are already use of its negated
value, we will have benefit as no extra Node is added.

Differential revision: https://reviews.llvm.org/D75501

(cherry picked from commit 3906ae387f0775dfe4426e4336748269fafbd190)

1 files changed, 101 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/PowerPC/fma-combine.ll b/llvm/test/CodeGen/PowerPC/fma-combine.ll
index 88da295201f..8973dc1334d 100644
--- a/llvm/test/CodeGen/PowerPC/fma-combine.ll
+++ b/llvm/test/CodeGen/PowerPC/fma-combine.ll
@@ -137,3 +137,104 @@ entry:
   %add = fsub double %mul, %a
   ret double %add
 }
+
+define float @fma_combine_no_ice() {
+; CHECK-FAST-LABEL: fma_combine_no_ice:
+; CHECK-FAST:       # %bb.0:
+; CHECK-FAST-NEXT:    addis 3, 2, .LCPI4_0@toc@ha
+; CHECK-FAST-NEXT:    addis 4, 2, .LCPI4_1@toc@ha
+; CHECK-FAST-NEXT:    lfs 0, .LCPI4_0@toc@l(3)
+; CHECK-FAST-NEXT:    lfsx 2, 0, 3
+; CHECK-FAST-NEXT:    addis 3, 2, .LCPI4_2@toc@ha
+; CHECK-FAST-NEXT:    lfs 3, .LCPI4_1@toc@l(4)
+; CHECK-FAST-NEXT:    lfs 1, .LCPI4_2@toc@l(3)
+; CHECK-FAST-NEXT:    xsmaddasp 3, 2, 0
+; CHECK-FAST-NEXT:    xsmaddasp 1, 2, 3
+; CHECK-FAST-NEXT:    xsnmsubasp 1, 3, 2
+; CHECK-FAST-NEXT:    blr
+;
+; CHECK-FAST-NOVSX-LABEL: fma_combine_no_ice:
+; CHECK-FAST-NOVSX:       # %bb.0:
+; CHECK-FAST-NOVSX-NEXT:    addis 3, 2, .LCPI4_0@toc@ha
+; CHECK-FAST-NOVSX-NEXT:    lfs 0, .LCPI4_0@toc@l(3)
+; CHECK-FAST-NOVSX-NEXT:    addis 3, 2, .LCPI4_1@toc@ha
+; CHECK-FAST-NOVSX-NEXT:    lfs 1, 0(3)
+; CHECK-FAST-NOVSX-NEXT:    lfs 2, .LCPI4_1@toc@l(3)
+; CHECK-FAST-NOVSX-NEXT:    addis 3, 2, .LCPI4_2@toc@ha
+; CHECK-FAST-NOVSX-NEXT:    fmadds 0, 1, 2, 0
+; CHECK-FAST-NOVSX-NEXT:    lfs 2, .LCPI4_2@toc@l(3)
+; CHECK-FAST-NOVSX-NEXT:    fmadds 2, 1, 0, 2
+; CHECK-FAST-NOVSX-NEXT:    fnmsubs 1, 0, 1, 2
+; CHECK-FAST-NOVSX-NEXT:    blr
+;
+; CHECK-LABEL: fma_combine_no_ice:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addis 3, 2, .LCPI4_0@toc@ha
+; CHECK-NEXT:    addis 4, 2, .LCPI4_1@toc@ha
+; CHECK-NEXT:    lfs 0, .LCPI4_0@toc@l(3)
+; CHECK-NEXT:    lfsx 2, 0, 3
+; CHECK-NEXT:    addis 3, 2, .LCPI4_2@toc@ha
+; CHECK-NEXT:    lfs 3, .LCPI4_1@toc@l(4)
+; CHECK-NEXT:    lfs 1, .LCPI4_2@toc@l(3)
+; CHECK-NEXT:    xsmaddasp 3, 2, 0
+; CHECK-NEXT:    xsmaddasp 1, 2, 3
+; CHECK-NEXT:    xsnmsubasp 1, 3, 2
+; CHECK-NEXT:    blr
+  %tmp = load float, float* undef, align 4
+  %tmp2 = load float, float* undef, align 4
+  %tmp3 = fmul fast float %tmp, 0x3FE372D780000000
+  %tmp4 = fadd fast float %tmp3, 1.000000e+00
+  %tmp5 = fmul fast float %tmp2, %tmp4
+  %tmp6 = load float, float* undef, align 4
+  %tmp7 = load float, float* undef, align 4
+  %tmp8 = fmul fast float %tmp7, 0x3FE372D780000000
+  %tmp9 = fsub fast float -1.000000e+00, %tmp8
+  %tmp10 = fmul fast float %tmp9, %tmp6
+  %tmp11 = fadd fast float %tmp5, 5.000000e-01
+  %tmp12 = fadd fast float %tmp11, %tmp10
+  ret float %tmp12
+}
+
+; This would crash while trying getNegatedExpression().
+define double @getNegatedExpression_crash(double %x, double %y) {
+; CHECK-FAST-LABEL: getNegatedExpression_crash:
+; CHECK-FAST:       # %bb.0:
+; CHECK-FAST-NEXT:    addis 3, 2, .LCPI5_1@toc@ha
+; CHECK-FAST-NEXT:    addis 4, 2, .LCPI5_0@toc@ha
+; CHECK-FAST-NEXT:    lfs 3, .LCPI5_1@toc@l(3)
+; CHECK-FAST-NEXT:    lfs 4, .LCPI5_0@toc@l(4)
+; CHECK-FAST-NEXT:    xssubdp 0, 1, 3
+; CHECK-FAST-NEXT:    xsmaddadp 3, 1, 4
+; CHECK-FAST-NEXT:    xsmaddadp 0, 3, 2
+; CHECK-FAST-NEXT:    fmr 1, 0
+; CHECK-FAST-NEXT:    blr
+;
+; CHECK-FAST-NOVSX-LABEL: getNegatedExpression_crash:
+; CHECK-FAST-NOVSX:       # %bb.0:
+; CHECK-FAST-NOVSX-NEXT:    addis 3, 2, .LCPI5_0@toc@ha
+; CHECK-FAST-NOVSX-NEXT:    addis 4, 2, .LCPI5_1@toc@ha
+; CHECK-FAST-NOVSX-NEXT:    lfs 0, .LCPI5_0@toc@l(3)
+; CHECK-FAST-NOVSX-NEXT:    lfs 3, .LCPI5_1@toc@l(4)
+; CHECK-FAST-NOVSX-NEXT:    fmadd 3, 1, 3, 0
+; CHECK-FAST-NOVSX-NEXT:    fsub 0, 1, 0
+; CHECK-FAST-NOVSX-NEXT:    fmadd 1, 3, 2, 0
+; CHECK-FAST-NOVSX-NEXT:    blr
+;
+; CHECK-LABEL: getNegatedExpression_crash:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addis 3, 2, .LCPI5_1@toc@ha
+; CHECK-NEXT:    addis 4, 2, .LCPI5_0@toc@ha
+; CHECK-NEXT:    lfs 3, .LCPI5_1@toc@l(3)
+; CHECK-NEXT:    lfs 4, .LCPI5_0@toc@l(4)
+; CHECK-NEXT:    xssubdp 0, 1, 3
+; CHECK-NEXT:    xsmaddadp 3, 1, 4
+; CHECK-NEXT:    xsmaddadp 0, 3, 2
+; CHECK-NEXT:    fmr 1, 0
+; CHECK-NEXT:    blr
+  %neg = fneg fast double %x
+  %fma = call fast double @llvm.fma.f64(double %neg, double 42.0, double -1.0)
+  %add = fadd fast double %x, 1.0
+  %fma1 = call fast double @llvm.fma.f64(double %fma, double %y, double %add)
+  ret double %fma1
+}
+declare double @llvm.fma.f64(double, double, double) nounwind readnone