[llvm] [InstCombine] optimize powi(X,Y) * X with Ofast (PR #69998)

[Matt Arsenault via llvm-commits]

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@@ -192,42 +225,42 @@ define double @powi_fmul_powi_same_power(double %x, i32 %y, i32 %z) {
 ; CHECK-NEXT:    ret double [[MUL]]
 ;
 entry:
-  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
-  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p1 = tail call reassoc double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p2 = tail call reassoc double @llvm.powi.f64.i32(double %x, i32 %y)
   %mul = fmul reassoc double %p2, %p1
   ret double %mul
 }
 
 define double @powi_fmul_powi_use_first(double %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @powi_fmul_powi_use_first(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Y:%.*]])
+; CHECK-NEXT:    [[P1:%.*]] = tail call reassoc double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Y:%.*]])
 ; CHECK-NEXT:    tail call void @use(double [[P1]])
 ; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[Y]], [[Z:%.*]]
 ; CHECK-NEXT:    [[MUL:%.*]] = call reassoc double @llvm.powi.f64.i32(double [[X]], i32 [[TMP0]])
 ; CHECK-NEXT:    ret double [[MUL]]
 ;
 entry:
-  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p1 = tail call reassoc double @llvm.powi.f64.i32(double %x, i32 %y)
   tail call void @use(double %p1)
-  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %z)
+  %p2 = tail call reassoc double @llvm.powi.f64.i32(double %x, i32 %z)
   %mul = fmul reassoc double %p1, %p2
   ret double %mul
 }
 
 define double @powi_fmul_powi_use_second(double %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @powi_fmul_powi_use_second(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Z:%.*]])
+; CHECK-NEXT:    [[P1:%.*]] = tail call reassoc double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Z:%.*]])
 ; CHECK-NEXT:    tail call void @use(double [[P1]])
 ; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[Y:%.*]], [[Z]]
 ; CHECK-NEXT:    [[MUL:%.*]] = call reassoc double @llvm.powi.f64.i32(double [[X]], i32 [[TMP0]])
 ; CHECK-NEXT:    ret double [[MUL]]
 ;
 entry:
-  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %z)
+  %p1 = tail call reassoc double @llvm.powi.f64.i32(double %x, i32 %z)
   tail call void @use(double %p1)
-  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p2 = tail call reassoc double @llvm.powi.f64.i32(double %x, i32 %y)
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arsenm wrote:

If we don't have a test where the 2 powi declarations have different integer types, should add one 

https://github.com/llvm/llvm-project/pull/69998