This patch imports https://reviews.llvm.org/D144469, extends the test pass introduced in that patch to decompose complex<T>, and add test cases that check that decomposition.. This patch extends the test pass for 1:N type conversion to convert complex<T> into T, T. This allows to convert complex numbers to built-in types in function signatures, adding materializations to the beginning and end of the function body where necessary. The commit also extends the test cases of ComplexToStandard such that the function signatures are converted either before that conversion or after. The additional checks show that, with very few exceptions, both orders lead to the same result, so the 1:N type conversion composes cleanly with other transformations. (The few exceptions are due to foldings or canonicalizations triggered in one order but not the other. This could be avoided by implementing a dedicated pattern application driver in the 1:N type conversion pass, instead of using applyPatternsAndFoldGreedily.)

This patch imports https://reviews.llvm.org/D144469, extends the test pass introduced in that patch to decompose complex<T>, and add test cases that check that decomposition. This patch extends the test pass for 1:N type conversion to convert complex<T> into T, T. This allows to convert complex numbers to built-in types in function signatures, adding materializations to the beginning and end of the function body where necessary. The commit also extends the test cases of ComplexToStandard such that the function signatures are converted either before that conversion or after. The additional checks show that, with very few exceptions, both orders lead to the same result, so the 1:N type conversion composes cleanly with other transformations. (The few exceptions are due to foldings or canonicalizations triggered in one order but not the other. This could be avoided by implementing a dedicated pattern application driver in the 1:N type conversion pass, instead of using applyPatternsAndFoldGreedily.) *Update:* I have created https://reviews.llvm.org/D145501 in the meantime, which only has the additions related to `complex`, which is what I actually wanted. I think that this diff is now superfluous.

This patch imports https://reviews.llvm.org/D144469, extends the test pass introduced in that patch to decompose complex<T>, and add test cases that check that decomposition.. This patch extends the test pass for 1:N type conversion to convert complex<T> into T, T. This allows to convert complex numbers to built-in types in function signatures, adding materializations to the beginning and end of the function body where necessary. The commit also extends the test cases of ComplexToStandard such that the function signatures are converted either before that conversion or after. The additional checks show that, with very few exceptions, both orders lead to the same result, so the 1:N type conversion composes cleanly with other transformations. (The few exceptions are due to foldings or canonicalizations triggered in one order but not the other. This could be avoided by implementing a dedicated pattern application driver in the 1:N type conversion pass, instead of using applyPatternsAndFoldGreedily.) *Update:* I have created https://reviews.llvm.org/D145501 in the meantime, which only has the additions related to `complex`, which is what I actually wanted. I think that this diff is now superfluous.