add testcases for PR30188

[sebpop]

Summary

Add testcases to llvm test/ to make sure that the combined middle-end
optimizations do not regress on optimizing the number of loads in the loops.

[spatel]

I thought we frown on multi-pass regression tests, let alone -O2.

Based on the comments in PR30188 ( https://llvm.org/bugs/show_bug.cgi?id=30188 ) - if the goal is to make sure that BinarySearch perf does not regress, is a better solution to add that C source app to test-suite's Benchmarks dir, so we can make sure that the end-to-end perf is what we want?

llvm/test/Transforms/Mem2Reg/pr30188-1.ll

+; RUN: opt < %s -O2 -S | grep load | count 1
+; RUN: opt < %s -O2 -S | not grep store
+
+; Check that the optimized code only contains one load in the innermost loop.
+
+define i32 @_Z4testfPf(float %exp, float* %array) {
+entry:
+  %exp.addr = alloca float, align 4
+  %array.addr = alloca float*, align 8
+  %hi = alloca i32, align 4
+  %lo = alloca i32, align 4
+  %offset = alloca i32, align 4
+  %delta = alloca i32, align 4
+  store float %exp, float* %exp.addr, align 4
+  store float* %array, float** %array.addr, align 8
+  store i32 255, i32* %hi, align 4
+  store i32 0, i32* %lo, align 4
+  store i32 0, i32* %offset, align 4
+  br label %while.cond
+
+while.cond:                                       ; preds = %if.end, %entry
+  %0 = load i32, i32* %hi, align 4
+  %1 = load i32, i32* %lo, align 4
+  %cmp = icmp sgt i32 %0, %1
+  br i1 %cmp, label %while.body, label %while.end
+
+while.body:                                       ; preds = %while.cond
+  %2 = load i32, i32* %hi, align 4
+  %3 = load i32, i32* %lo, align 4
+  %sub = sub nsw i32 %2, %3
+  %div = udiv i32 %sub, 2
+  store i32 %div, i32* %delta, align 4
+  %4 = load i32, i32* %delta, align 4
+  %cmp1 = icmp ugt i32 1, %4
+  br i1 %cmp1, label %cond.true, label %cond.false
+
+cond.true:                                        ; preds = %while.body
+  br label %cond.end
+
+cond.false:                                       ; preds = %while.body
+  %5 = load i32, i32* %delta, align 4
+  br label %cond.end
+
+cond.end:                                         ; preds = %cond.false, %cond.true
+  %cond = phi i32 [ 1, %cond.true ], [ %5, %cond.false ]
+  store i32 %cond, i32* %delta, align 4
+  %6 = load i32, i32* %lo, align 4
+  %7 = load i32, i32* %delta, align 4
+  %add = add i32 %6, %7
+  store i32 %add, i32* %offset, align 4
+  %8 = load i32, i32* %offset, align 4
+  %idxprom = sext i32 %8 to i64
+  %9 = load float*, float** %array.addr, align 8
+  %arrayidx = getelementptr inbounds float, float* %9, i64 %idxprom
+  %10 = load float, float* %arrayidx, align 4
+  %11 = load float, float* %exp.addr, align 4
+  %cmp2 = fcmp ogt float %10, %11
+  br i1 %cmp2, label %if.then, label %if.else
+
+if.then:                                          ; preds = %cond.end
+  %12 = load i32, i32* %hi, align 4
+  %13 = load i32, i32* %delta, align 4
+  %sub3 = sub i32 %12, %13
+  store i32 %sub3, i32* %hi, align 4
+  br label %if.end
+
+if.else:                                          ; preds = %cond.end
+  %14 = load i32, i32* %lo, align 4
+  %15 = load i32, i32* %delta, align 4
+  %add4 = add i32 %14, %15
+  store i32 %add4, i32* %lo, align 4
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then
+  br label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %16 = load i32, i32* %offset, align 4
+  ret i32 %16
+}

llvm/test/Transforms/Mem2Reg/pr30188.ll

+; RUN: opt < %s -O2 -S | grep load | count 3
+; RUN: opt < %s -O2 -S | not grep store
+
+; Check that the optimized code only contains one load in the innermost loop.
+
+%struct.a = type { i32, %struct.b* }
+%struct.b = type { i32 }
+
+define i32 @BinarySearch(%struct.a* %input, i32 %t.coerce) {
+entry:
+  %retval = alloca i32, align 4
+  %t = alloca %struct.b, align 4
+  %input.addr = alloca %struct.a*, align 8
+  %low = alloca i32, align 4
+  %high = alloca i32, align 4
+  %mid = alloca i32, align 4
+  %coerce.dive = getelementptr inbounds %struct.b, %struct.b* %t, i32 0, i32 0
+  store i32 %t.coerce, i32* %coerce.dive, align 4
+  store %struct.a* %input, %struct.a** %input.addr, align 8
+  %0 = load %struct.a*, %struct.a** %input.addr, align 8
+  %l_ = getelementptr inbounds %struct.a, %struct.a* %0, i32 0, i32 0
+  %1 = load i32, i32* %l_, align 8
+  %cmp = icmp sgt i32 %1, 0
+  br i1 %cmp, label %if.then, label %if.end7
+
+if.then:                                          ; preds = %entry
+  store i32 0, i32* %low, align 4
+  %2 = load %struct.a*, %struct.a** %input.addr, align 8
+  %l_1 = getelementptr inbounds %struct.a, %struct.a* %2, i32 0, i32 0
+  %3 = load i32, i32* %l_1, align 8
+  store i32 %3, i32* %high, align 4
+  br label %while.cond
+
+while.cond:                                       ; preds = %if.end, %if.then
+  %4 = load i32, i32* %high, align 4
+  %5 = load i32, i32* %low, align 4
+  %add = add nsw i32 %5, 1
+  %cmp2 = icmp ne i32 %4, %add
+  br i1 %cmp2, label %while.body, label %while.end
+
+while.body:                                       ; preds = %while.cond
+  %6 = load i32, i32* %high, align 4
+  %7 = load i32, i32* %low, align 4
+  %add3 = add nsw i32 %6, %7
+  %div = sdiv i32 %add3, 2
+  store i32 %div, i32* %mid, align 4
+  %8 = load i32, i32* %mid, align 4
+  %idxprom = sext i32 %8 to i64
+  %9 = load %struct.a*, %struct.a** %input.addr, align 8
+  %data_ = getelementptr inbounds %struct.a, %struct.a* %9, i32 0, i32 1
+  %10 = load %struct.b*, %struct.b** %data_, align 8
+  %arrayidx = getelementptr inbounds %struct.b, %struct.b* %10, i64 %idxprom
+  %x_ = getelementptr inbounds %struct.b, %struct.b* %arrayidx, i32 0, i32 0
+  %11 = load i32, i32* %x_, align 4
+  %x_4 = getelementptr inbounds %struct.b, %struct.b* %t, i32 0, i32 0
+  %12 = load i32, i32* %x_4, align 4
+  %cmp5 = icmp sgt i32 %11, %12
+  br i1 %cmp5, label %if.then6, label %if.else
+
+if.then6:                                         ; preds = %while.body
+  %13 = load i32, i32* %mid, align 4
+  store i32 %13, i32* %high, align 4
+  br label %if.end
+
+if.else:                                          ; preds = %while.body
+  %14 = load i32, i32* %mid, align 4
+  store i32 %14, i32* %low, align 4
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then6
+  br label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %15 = load i32, i32* %low, align 4
+  store i32 %15, i32* %retval, align 4
+  br label %return
+
+if.end7:                                          ; preds = %entry
+  store i32 -1, i32* %retval, align 4
+  br label %return
+
+return:                                           ; preds = %if.end7, %while.end
+  %16 = load i32, i32* %retval, align 4
+  ret i32 %16
+}